Thanks but I think the problem is not in the driver itself because it never crashed and other games not related to JPCSP work properly and even if I try using integrated graphic card JPCSP doesn't show anything (it usually reaches title screen before crashing for low graphic performances)... I also never had any problem with previous versions (320.49 or lower) wich is the case discussed in the post you suggested. Anyway I'll try that as the last option, if possible ask other people to read this post and help me! 
p.s. i wrote about the nvidia driver because it was the only change I could think of apart from updating java 7 update 40 so the problem could be anywhere else in the computer xD
p.p.s. added a screenshot of what I see when I try to play, different colors in JPCSP window are the results of the game going on without the video...
p.s. i wrote about the nvidia driver because it was the only change I could think of apart from updating java 7 update 40 so the problem could be anywhere else in the computer xD
p.p.s. added a screenshot of what I see when I try to play, different colors in JPCSP window are the results of the game going on without the video...