someone please help me with my counter strike problem

[SgtBhind]

i just reformatted my computer and now every time i try to play counter strike source or day of defeat source it always reboots my computer after 5 seconds on the loading screen. can someone please help me im going NUTS.i tried installing the windows XP driver from nvidia.com but it keeps saying cant find devices and it cancels.(it used to work).

i have a geforce 6200 agp
AMD Athlon(tm)XP 3100+
2.20 GHz, 2 GB ram

 

[SgtBhind]

im so lonely without counter strike source and day of defeat source