I get an error reading "This program has performed an illegal operation". whenever i start to play games.i am able to run the game but graphics in the game is distorted and after bout 2 mins of its running this error comes.

The error specifies the MODULE name as ntdll.dll.....i dunno what to do.. i have tried reinstalling the driver but no use ....I even reinstalled the OS...
There wasnt any problem @ the beginning....it all started a week ago...
HELP me guys ....and lemme play....

specs

AMD XP 1 ghz
Geforce fx5200
ASUS motherboard
1 gb ddr ram



WILL IT BE A HARDWARE PROBLEM?????????????