Sorta ... but possibly not quite all that simple. ATI cards and Via motherboard chipsets are known to have issues with one another, particularly in the WinXP environment. Updating your graphics drivers and your machine's BIOS are prolly good ideas. the ATI website has quite a collection of articles referencing
VPU problems.
With luck, yours will turn out to be a simple software issue - it seems thats pretty common. However, there also might be hardware issues ranging from cooling through power supply to RAM. Good luck.