It is possible for the ati2dvag blue screen problem to cause unwanted system freezes and cause your CPU to run at 100%. Sometimes your system is unable to boot and a blue screen of death is displayed
How To Fix : Reseat the ATI video card in its slot. It could be a lose connection on the card that is causing the ati2dvag blue screen of death issue. Remove your ATI video card, and blow the connections on the video card and on the motherboard. Then carefully insert the video card back in to the same slot
Install older drivers of the ATI video card. Remove the current ATI video card driver by going in to Control Panel, then System, click on Hardware, then Device Manager and then choose to uninstall the device driver in Display Adaptors. Reboot your system. Now install the older drivers. Google for older drivers
Are power settings the cause? Have you changed any power settings recently? If yes set your power settings to "Maximum Performance" to see if the issue goes away