Spybot,virus burster ,spy shredder and a few more are im afraid viruses themselves ,until that is ,you download the full version and pay for it .Crafty b*****ds bring down trojons every time you scan ,they then delete some of them as you request but the residue is what is slowing down your pc ,especially on start up .Take my advce and download the 'superantispyware 'and see what they say ?.The only free protection on the web that removes everything and all its components and is compatible with AVG.