SC 13G/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G/A

Under the Securities Exchange Act of 1934

(Amendment No. 4)*

QUEST SOFTWARE, INC.

(Name of Issuer)

COMMON STOCK, no par value

(Title of Class of Securities)

74834 T 10 3

(CUSIP Number)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

¨    Rule 13d-1(b)

¨    Rule 13d-1(c)

x    Rule 13d-1(d)

* The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act, but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13G/A

CUSIP No. 74834 T 10 3 Page 2 of 5 Pages

1	NAME OF REPORTING PERSONS/ I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) David M. Doyle
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (SEE INSTRUCTIONS) (a)  ¨ (b)  ¨
3	SEC USE ONLY
4	CITIZENSHIP OR PLACE OF ORGANIZATION United States of America

NUMBER OF SHARES REPORTING BENEFICIALLY OWNED BY EACH PERSON WITH	5	SOLE VOTING POWER 9,155,8421
	6	SHARED VOTING POWER 462,2922
	7	SOLE DISPOSITIVE POWER 9,155,8421
	8	SHARED DISPOSITIVE POWER 462,2922

9	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 9,618,134 1,2
10	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES  ¨ (See Instructions)
11	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9) 10.3% (based on shares outstanding on December 31, 2003)
12	TYPE OF REPORTING PERSON (See Instructions) IN

Item 1.	(a)	Name of Issuer: Quest Software, Inc.
	(b)	Address of Issuer’s Principal Executive Offices:
		8001 Irvine Center Drive
		Irvine, California 92618
Item 2.	(a)	Name of Person Filing: David M. Doyle
	(b)	Address of Principal Business Office:
		8001 Irvine Center Drive
		Irvine, California 92618
	(c)	Citizenship: United States of America.
	(d)	Title of Class of Securities: Common Stock, no par value
	(e)	CUSIP Number: 74834 T 10 3
Item 3.	If this statement is filed pursuant Rule 13d-1(b), or 13d-2(b), check whether the person filing is a:
	(a)	¨	Broker or dealer registered under Section 15 of the Act;
	(b)	¨	Bank as defined in Section 3(a)(6) of the Act;
	(c)	¨	Insurance Company as defined in Section 3(a)(19) of the Act;
	(d)	¨	Investment Company registered under Section 8 of the Investment Company Act;
	(e)	¨	Investment Advisor registered under Section 203 of the Investment Advisors Act of 1940;
	(f)	¨	Employee Benefit Plan, Pension Fund which is subject to the provisions of the Employee Retirement Income Security Act of 1974 or Endowment Fund; see Rule 13d-1(b)(1)(ii)(F)
	(g)	¨	Parent Holding Company, in accordance with Rule 13d-1(b)(ii)(G) (Note, See Item 7);
	(h)	¨	Group, in accordance with Rule 13d-1(b)(1)(ii)(H).
	If this statement is filed pursuant to 13d-1(c), check this box. ¨
Item 4.	Ownership.
	(a)	Amount beneficially owned: 9,618,134 1,2 shares of Common Stock
	(b)	Percent of Class: 10.3% (based on shares outstanding on December 31, 2003)
	(c)	Number of shares as to such person has:
		(i)	sole power to vote or to direct the vote of:	9,155,8421
		(ii)	shared power to vote or to direct the vote of:	462,2922
		(iii)	sole power to dispose or to direct the disposition of:	9,155,8421
		(iv)	shared power to dispose or to direct the disposition of:	462,2922
Item 5.	Ownership of 5% or Less of Class.
	If this statement is being filed to report the fact that as of the date hereof the reported person has ceased to be the beneficial owner of more than 5% of the class of securities, check the following:  ¨

3

Item 6.	Ownership of More Than 5% on Behalf of Another Person
	Not applicable.
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company
	Not applicable.
Item 8.	Identification and Classification of Members of the Group.
	Not applicable.
Item 9.	Notice of Dissolution of Group.
	Not applicable.
Item 10.	Certification.
	Not applicable.

¹ Includes 62,500 shares issuable upon exercise of stock options that are exercisable within 60 days of December 31, 2003. Includes 1,000,000 shares that are subject to a variable delivery forward contract entered into by the Reporting Person on November 4, 2002. Includes an aggregate of 1,869,000 shares that are subject to variable delivery forward contracts entered into by the Reporting Person during the period from January 1, 2003 to December 31, 2003 pursuant to a 10b5-1 trading plan adopted by the Reporting Person on December 10, 2002, a copy of which trading plan is attached hereto as Exhibit 99.1.

² Includes 134,740 shares held by the Doyle Charitable Remainder Trust, of which the Reporting Person is the trustee, and 327,552 shares owned by DMD Partnership.

4

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Date: February 17, 2004	/S/    DAVID M. DOYLE
	Name: David M. Doyle

5

EXHIBIT INDEX

Exhibit No.	Description of Document
99.1	10b5-1 Trading Plan adopted by David M. Doyle on December 10, 2002

EX-99.1

Exhibit 99.1

Advanced Instruction to Sell Common Stock

To:	Deutsche Bank Securities Inc. (“DBSI”), acting in its individual capacity and/or as agent for Deutsche Bank AG, London branch (“DBAG”)
Dated:	December 10, 2002
Account Number:	231-73351

I am a holder of shares, or options to acquire shares, of the common stock of Quest Software, Inc. (the “Company”). I would like to sell Company shares in order to diversify my portfolio pursuant to this instruction (the “Instruction”). I also wish to take advantage of SEC Rule 10b5-1, which provides for an affirmative defense from insider trading liability for purchases and sales effected pursuant to a contract, instruction or plan entered into when a person is not aware of any material nonpublic information. I am giving this Instruction in good faith and not as part of a plan or scheme to avoid the prohibitions of Rule 10b5-1. I have confirmed with my own legal advisors and with Corporate Counsel of the Company that I am eligible to sell under the safe harbor provisions, understand my ongoing obligations under such provisions, and am not relying upon any advice of DBSI or its affiliates with regard thereto. While this Instruction is in effect, I agree not to enter into or alter any corresponding or hedging transaction or position with respect to the securities covered by this Instruction and agree not to alter or deviate from, or attempt to exercise any influence over how, when or whether transactions are executed pursuant to, the terms of this Instruction.

I hereby instruct DBSI to sell for my account up to 4,000,000 shares of Company stock in the days in which the primary market for the Company’s stock is open in accordance with the conditions set out below. This Instruction shall be valid and binding for the period from January 1, 2003 to December 31, 2003, inclusive, and may not be revoked unless in writing, which revocation shall be effective 3 business days after it is received by DBSI or DBAG, as appropriate, pursuant to the contact information listed below.

I wish to sell shares using one or more Variable Delivery Forward contracts (the “VDF”s). In connection therewith, I have executed a Forward Purchase Contract, and the associated Pledge and Security Annex and Account Control Agreement (the “VDF Contracts”) with DBAG. This letter constitutes an offer by me to DBAG to enter into one or more VDFs upon the terms listed in the VDF Contracts and the following terms:

1. The Shares shall be sold in 4 quarterly periods, whereby a maximum of 1,000,000 shares per period can be sold.

2. For the period from January 1, 2003 to March 31, 2003, inclusive:

(a) If the Company stock price is between $5.00 and $9.99, then sell a maximum of 50,000 shares.

(b) If the Company stock price is between $10.00 and $12.49, then sell a maximum of 200,000 shares plus any unsold shares from 2(a).

(c) If the Company stock price is between $12.50 and $19.99, then sell a maximum of 250,000 shares plus any unsold shares from 2(a) and 2(b).

(d) If the Company stock price is $20.00 or greater, then sell a maximum of 500,000 shares plus any unsold shares from 2(a), 2(b) and 2(c).

3. For the period from April 1, 2003 to June 30, 2003, inclusive:

(a) If the Company stock price is between $5.00 and $9.99, then sell a maximum of 50,000 shares.

(b) If the Company stock price is between $10.00 and $12.49, then sell a maximum of 200,000 shares plus any unsold shares from 3(a).

(c) If the Company stock price is between $12.50 and $19.99, then sell a maximum of 250,000 shares plus any unsold shares from 3(a) and 3(b).

(d) If the Company stock price is $20.00 or greater, then sell a maximum of 500,000 shares plus any unsold shares from 3(a), 3(b) and 3(c).

4. For the period from July 1, 2003 to September 30, 2003, inclusive:

(a) If the Company stock price is between $5.00 and $9.99, then sell a maximum of 50,000 shares.

(b) If the Company stock price is between $10.00 and $12.49, then sell a maximum of 200,000 shares plus any unsold shares from 4(a).

(c) If the Company stock price is between $12.50 and $19.99, then sell a maximum of 250,000 shares plus any unsold shares from 4(a) and 4(b).

(d) If the Company stock price is $20.00 or greater, then sell a maximum of 500,000 shares plus any unsold shares from 4(a), 4(b) and 4(c).

5. For the period from October 1, 2003 to December 31, 2003, inclusive:

(a) If the Company stock price is between $5.00 and $9.99, then sell a maximum of 50,000 shares.

(b) If the Company stock price is between $10.00 and $12.49, then sell a maximum of 200,000 shares plus any unsold shares from 5(a).

(c) If the Company stock price is between $12.50 and $19.99, then sell a maximum of 250,000 shares plus any unsold shares from 5(a) and 5(b).

(d) If the Company stock price is $20.00 or greater, then sell a maximum of 500,000 shares plus any unsold shares from 5(a), 5(b) and 5(c).

6. The Floor Level of each VDF shall be equal to 100%.

7. The Threshold Level of each VDF shall equal 120%.

8. The Valuation Date of each VDF shall be 2 years from the Trade Date.

9. The Purchase Price or advance rate of each VDF shall not be less than 89.1%.

10. Notwithstanding the terms contained herein, DBAG shall have sole discretion as to the number of VDFs executed, the Trade Date of each VDF, and the number of shares allocated to each VDF.

Any and all representations in the VDF Contracts and the VDF confirmation are incorporated herein and made as of the date hereof, and such representations shall be deemed repeated each day that this Instruction is in effect. This offer shall be deemed accepted once the conditions above have been met and at such time I shall be responsible for performance under the VDF Contracts and the VDF confirmation corresponding to such trade (which confirmation I agree to execute and return promptly). DBAG may accept this offer in whole or in part.

You are authorized to make deliveries of securities and payment of moneys in accordance with your normal practice. All shares to be sold shall have been previously deposited into my account, and you shall not be required to follow this Instruction if shares are not present in my account (or acceptable arrangements to deliver option shares have not been made) prior to the dates on which sales shall occur. The share amount listed above shall be increased or decreased to reflect stock splits or any other event with dilutive or concentrative effects should they occur. I understand that I shall be responsible to arrange for any filings that may be required under applicable law (e.g., Form 144, Schedule 13D, and Forms 4 and 5), and that I may be subject to the short swing profit rules contained in Section 16 of the Securities Exchange Act of 1934. In this connection, I understand that upon my request, you will assist me in making advance arrangements regarding the filing of Forms 144. Lastly, I hereby authorize you to notify Corporate Counsel of the Company of the execution of any VDF no later than the third business day after the Trade Date. This authorization does not otherwise relieve me of any responsibilities hereunder or under any applicable law.

All sales shall be effected in your normal fashion in accordance with Rule 144 and with your terms and conditions for my account and risk. You may act as principal in any transaction hereunder. I hereby ratify and confirm any and all transactions with you in accordance with this Instruction. I also agree to indemnify and hold DBSI and its affiliates harmless from and to pay DBSI and its affiliates promptly on demand any and all losses arising from its reasonable interpretation and performance of this Instruction. DBSI and its affiliates shall not be liable for the taking of any action or the omission to take any action hereunder except for actions or omissions that are a result of bad faith and gross negligence.

I am not presently aware of any material nonpublic information regarding the Company or its common stock, and covenant that I will not discuss or otherwise disclose material nonpublic information to my investment representative or any other of your personnel responsible for carrying out this Instruction. I certify that this Instruction does not violate or conflict with any law, regulation, employment plan, policy, contract, judgment, order, decree or undertaking applicable to me or to which I am a party, and agree to notify you if this representation is no longer accurate.

This Instruction shall be governed by the laws of New York. This Instruction shall not be effective until DBSI or DBAG, as appropriate, confirms its acceptance in writing by signing below. DBSI or DBAG may decline to act hereunder in their sole discretion upon reasonable notice.

/s/    DAVID DOYLE        

David Doyle

Accepted (for Doyle VDF)

Deutsche Bank AG London

c/o Deutsche Bank Securities Inc.

Attn: Paul Somma

31 W. 52nd St.

NY, NY 10019

Fax #: 415-617-3385

/s/    PAUL SOMMA         

By: Paul Somma