San Andreas works fine and everything, but when I enter a building (from outside into house to save or anything), it automatically restarts the computer

Operating System: Windows XP Home Edition (5.1, Build 2600) Service Pack 2
Processor: Intel(R) Pentium(R) 4 CPU 3.00GHz (2 CPUs)
Card name: C.P. Technologies Inc. RADEON X300SE
Manufacturer: ATI Technologies Inc.
Chip type: RADEON X300 SE (0x5B60)
DAC type: Internal DAC(400MHz)
Display Memory: 128.0 MB
Driver Version: 6.14.0010.6542 (English)

Any suggestions?

EDIT
I updated the driver, re-installed direct x 9.0c, and also ran a recovery on the comp (not that i did it for the game, i had a virus or somethin)