CPU always at 100%

My CPU is always at 100%, and the task manager reveals nothing that is taking up any of my cpu, yet it remains at 100%, idling or not. My system was running great for months with virus software running until it randomly started doing this. No updates were installed, nothing has been installed in over a week. If anyone can give me any idea why this is happening I would very much appreciate it.
Thanks

What AV are you using? And list more details about your system like version, amount of ram etc.
Joe

If your CPU is running that much, Task Manager (showing all users) has to show it. You can also check the Resource Monitor for information.

As Joe S brings up, anti-virus scans can take quite a bit of time, as can some backup utilities and a few other misbehaving utilities.

You might boot into safe mode to see if it continues.

Let us know if you see anything.

My system is running on the Avast anti-virus and is
Toshiba Satellite
intel Celeron CPU 900@ 2.20GHz
4GB Ram

I was checking the Task Manager showing all users and it didn't show any processes using more than 01 cpu. I'm not really sure how to check the resource monitor, or what that is but I'll check it out.

Booting in Safe Mode eliminates the problem.

I uninstalled Avast after I heard it wasn't as good as MSE, that fixed the problem

Thanks for letting us know.

Make sure you run their cleanup tool and the ones for any other AV you had on in the past. You find them on the AV maker's site
Joe