What is my computer doing when it is so slow and supposedly 90% idle?

Why is my computer soooooo slow and unresponsive when task manager says the active processes are say 10% and the computer supposedly 90% Idle? What is going on? How can I find out who the culprit is? Is there a hidden process somewhere or are the stats simply unreliable?
The computer is not always like this, but it should be possible to work out what the problem is whenever it is such a huge slowdown!
I'm looking for some better tools and some general thoughts.
Oh, and it's XP3 on an E2200 with 2GB and 1TB.
Thanks.

 

Run mbam if you can, and post in the malware forum if your system resources have become increasingly pathetic.

:major

 

Thanks too.
Started running mbam after I first posted, in full mode (7 hours! to scan 1076055 objects). Found and deleted "Rouge.Multiple" registry key, "Adware.Yabector", and "Trojan.Banker" in wuasirvy.dll.
My computer was running incredibly slowly during the scan, perhaps expected? (Although Firefox has also been giving me grief, including lock-ups) over last 24 hours auto-updating itself to v12.)
It seems back to normal at the moment.

But severe slowdowns (and non-responsive programs) are fairly common experiences and I'm looking for good tools to identify what the holdup is and who is responsible in those cases. And how can a computer be 100 times slower than normal and yet be 90% idle?

 

Hi my friend , a good point is creating this cd

http://forum.avira.com/wbb/index.php?page=Thread&postID=730130

from a clean machine checking your system :wave

 

BigAussieD, welcome to MGs.
Please work your way through the Read & Run Me First.
Please be diligent and take your time. If you have issues, make a note of the same- and continue on to the next step of instructions.
Once you have the requested logs please attach the same in a new thread started in Malware Removal.

Cheers..

 

Sounds too me you need to defrag your HD after all the scans.

 

Also check the temperatures of your computer -> SpeedFan.

 

I'm wondering if your firewall or some other active security software could be slowing things.

What security apps are you using?
Also, just to be sure, check the Virtual Memory setting (paging file) is set to System managed size

An alternative to SpeedFan recommended by pwilliner is Speccy

I found it easier to read - has a nice interface and provides a lot of information.
Look at the screen shot on the download page.

 

Agreed Speed fan is really no good i would all so recommend Speccy it will give up to date temps every sec