Aspire 5100, Need help with CPU issue

Whenever I have Firefox, Winamp, or any single program open, my CPU usage frequently jumps up to 100%, hover around 40-60%, and rarely does it go back down to <10%. When idle, CPU usage jumps to around 60% then back down to around 5%.
I figured its a driver issue so I updated everything but everything seems to be fine when I used the update drivers using Device Manager, looking at Acer's driver downloads, and manufacturer's websites. No change.
I scanned my computer using Panda's online scanner, ad-aware, and spybot. Found nothing.
I then uninstalled my programs one by one until I removed every program I installed but I still didn't find what the cause of all this might be.
I reformatted my hard drive using killdisk and reinstalled vista (both using recovery disc and a Vista cd) and somehow CPU usage is still fluctuating between 50-100%.
Can anyone help me resolve this issue?

I have an Acer Aspire 5100 notebook
AMD Turion X2 TL-52 1.60 GHz
1790MB RAM
ATI Xpress 1100

Thank you very much for your time.

P.S.
I opened resource manager and saw that CPU usage jumps to 100% whenever the Maximum frequency drops to 50%.
Power plan is at High Performance, is it normal for the frequency to drop to 50%?
Ato, I thought that using notebook hardware control might be a temporary fix by controlling the CPU through it but I don't know how to configure it.
Once more, thank you.

P.P.S.
I'm running Windows Vista Home Premium

 

If you have Vista, it's normal. Vista is working in the background to cache things and whatnot. If you find it to be slowing down your computer, you can turn off things like Shadow Copy, Indexing and such.

 

Thank you for that fast reply.
It didn't slow me down that much before but I'll try turning them off and see what happens.


It was fine after I restarted but the CPU usage started jumping up again and started slapping me with unbearable lag in firefox after a while.
Any other suggestions?

 

I have the exact same problem and exact same laptop!!

I searched google, and found this post:
http://forum.notebookreview.com/showthread.php?t=204245

I tried doing what that guy did, but my computer still has problems. I don't know why it started happening recently... I really want to fix this problem!

 

Anyone else have any ideas?

Here's a short instance of CPU usage in Resource Monitor.
I've now installed most of my usual softwares (only steam(cs1.6), coreavc(gives me error when I try to configure it, and sidebar gadgets left)
The frequency of the spikes has gone down when I have 2 windows open but it still spikes if both are active (firefox and winamp or windows explorer and an IM)
When I use anything else CPU usage almost never go down below 60%

 

hi,

I have the same exact computer and the same problem. I would like to know if their is a solution.

 

Try checking the E-PowerManagement software. This controls the CPU speed, backlight etc and is acer software that was bundled with the machine. Unfortunately it tends to reset itself at random. The default setting for it is low so the CPU will be stepped right down. Turning the CPU speed back up to max and saving usually cures this fault