Your system running slow. It may not be a virus.

The other day, I decided that I was sick and tired of my slow system. As I try out lots of software, I thought I might have gotten infected by a virus or spyware. After running detailed scans of my system, no problems were found, but still the system was slow.
I ran a detailed disk check, including sectore recovery. After that, the system was back up to its normal speedy self.
It appears that I has a number of disc errors, that the scan corrected. These errors were causing the system to perform multiple retries, and hence the slow performance.