nvidia geforce 7300 GS keeps crashing after while when ever i play games.the screen goes all greenish with dots and the screen starts to act weird then it crashes.eventually the monitar says "windows XP has crashes.to prevent damages system will now reset" why is this problem.im really starting to get made at my computer.i cant really explain what exacly happends but please i need a way to fix this!im using a AMD mother board.1 GB ram.and a sata hard drive.why does this keep happening!!?