woodchip, Thanks for those links, I have Ad-Aware, Spywareblaster,Spybot SD, CCleaner and Avast. I went to Trend-Micro for the online scan, but it told me 3 1/2 hrs to check. so I will do that later.
I think it is something to do with the DLLCache, as indicated by Avast stopping at that whilst scanning, would you know anything about that please? I have downloaded and opened Spiceworks, so will now have a look at that.