Your computer can also be running slow for other reasons such as to many programs and processes running at the same time.
It could also be from your hardware.
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If you want to make sure it is not malware of any kind try this -
First download kasperskies tdsskiller. -
http://support.kaspersky.com/faq/?qid=208283363
Run a scan with it,it will tell you if you have a rootkit or not and remove it.
I also suggest running trend micro's house call -
http://housecall.trendmicro.com/
Last and not least try running spybot to see if there is any spyware -
http://www.safer-networking.org/index2.html
Post the results of each here.
If none of these programs find an infection I doubt the problem is malware.
IF this is the case I can help you step by step make your system alot faster.