STOCK-BASED COMPENSATION (Details) (USD $)	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011	May 31, 2010	May 31, 2009	May 31, 2008	May 31, 2007
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Balance (in shares)	3,610,000	3,850,000	17,150,236	19,961,797	14,972,381	12,535,048	6,886,652
Balance (in dollars per share)	$ 0.55	$ 0.65	$ 0.3	$ 0.27	$ 0.51	$ 0.58	$ 0.64
Granted (in shares)	0	0	0	0	14,427,600	5,365,197	5,824,000
Granted (in dollars per share)						$ 0.21	$ 0.49
Exercised (in shares)	0	0	(2,227,864)	(2,228,364)	0	0	(175,604)
Exercised (in dollars per share)			$ 0.01	$ 0.01			$ 0.01
Expired or cancelled (in shares)	(650,000)	(240,000)	(11,072,372)	(583,197)	(9,438,184)	(2,927,864)	0
Expired or cancelled (in dollars per share)	$ 0.75	$ 0.83	$ 0.30	$ 0.25		$ 0.22	$ 0
Balance (in shares)	2,960,000	3,610,000	3,850,000	17,150,236	19,961,797	14,972,381	12,535,048
Balance (in dollars per share)	$ 0.29	$ 0.55	$ 0.65	$ 0.3	$ 0.27	$ 0.51	$ 0.58
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share)	$ 0.02				$ 0.25
Expired or cancelled (in dollars per share)					$ 1.20
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in dollars per share)	$ 0.01				$ 0.15
Expired or cancelled (in dollars per share)					$ 0.25