I never used PrevX CSI before, but reading this thread I decided to give it a try and check out if Kaspersky 7 gives any warning. Download - OK...
Just my 2cents: Check the S.M.A.R.T status of your drive. HDDs aren't supposed to make strange noises. Spybot S&D and Spyware Blaster don't...
An installation of "Spybot Search & Destroy" and "Spyware Blaster" may be a good idea too.
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