hi flowerr,
You might want to have a look at this link, as you say you've removed some unspecified malware (rootkit) recently:
http://forum.avast.com/index.php?topic=53253.0You'll need to download and run these four programs: AdwCleaner, Malwarbytes (you've already got that one), OTL, and aswMBR. Why? Because we're talking about a rootkit, not some generic Trojan or unwanted toolbars.
Attach all four resulting logs in your next reply, and I will then go and notify a certified malware expert.
Along the way, am certain your defragging issue will also be addressed. Could be just a symptom, and not the source of your problem.