Having the same problem and no it isn't overheating and I have the latest drivers for everything.
http://www.myimg.us/images/06.25.09/9277.png
http://www.myimg.us/images/06.25.09/9278.png
Vista x64 Home Prem
Core2 Q6600 2.8 Ghz
8 GB DDR2-800 RAM
Geforce 8800 GTS 512 MB