CPU Usage at 100% with no programs running

Please, I am in dire need of assistance.

After booting up, with only one or two programs running, my CPU usage will very quickly spike to >85%, hovering at 100 most of the time. It has only started doing this in the past few days too, and has been very frustrating. I have checked my processes and there isn't anything running (even in SYSTEM) that would be taking up so much CPU. I have run anti-virus programs such as Ad-aware (NOD32 trial expired, I got lazy and stopped setting back my internal clock :P)

Wait. You went into task manager and under the process tab, even though your CPU is at 100% there is NOTHING listed as using CPU time? Do you have the CPU column enabled on the processes tab? You should see *something* in there running. If you click on the column title you can get it to sort by CPU use, you might need to click twice depending if the biggest user ends up at the bottom of the list and not the top. This is how I figure out what's eating my CPU time. --ch