Exception in system thread not managed on Windows 8
Exception in system thread not managed on Windows 8
You're experiencing the system thread exception message repeatedly every few minutes. It seems unrelated to your recent catalyst update, but it's happening now. The driver IRQ issues you mentioned might be contributing. Keep an eye on the situation and try to post again soon.
Power on in safe mode, remove all graphics drivers, and then install the newest versions from the maker's site.
Avoid waiting too long; just enable safe mode if needed, unless you have to. This should likely resolve the issue.
It should launch from your BIOS and appear in the startup or boot menu. This can be managed through OSA settings.