Re: Locking up
Lockup freeze and reboot can be caused by overheating, but what it can be also is a driver issue. In win xp instead of blue screening, the system will simply reboot.
Make sure you have the most recent drivers for your motherboard, also make sure you have the most recent version of directx (they update it now about once every two months). There is also a more recent official beta driver on nzone.com for your graphics card. Make sure you have all windows updates as well.