7. INCOME TAXES (Details 2)	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Reconciliation of Federal Statutory Rate to Effective Rate
U.S. federal statutory tax rate	34.00%	34.00%	34.00%
State taxes, net of federal tax effect	(0.40%)	(0.20%)	(0.60%)
Foreign rate differential	0.20%	2.90%	12.40%
Stock-based compensation	(4.40%)	(6.00%)	(8.50%)
Research and development credit	3.00%	0.10%	0.00%
Change in valuation allowance	(33.00%)	(30.20%)	(35.70%)
Other	(0.30%)	(0.20%)	(0.20%)
Effective tax rate	(0.90%)	0.40%	1.40%