Hello Viticus and welcome to the forum.
Before doing anything as drastic as a clean install, which is not necessarily a bad idea, just one you might want to save for a last ditch resolution and if it's hardware related won't help much anyway.
Watching you CPU is a good idea, but don't neglect your Disk I/Os, memory and network. Maybe use Resource Monitor to watch it over a period of time.
I would first suggest though, that you employ something called a "Clean Boot" and see if the computer does the same thing.
Have a look here for a guide
http://support.microsoft.com/kb/929135/
Good luck and keep us posted.