Really need computer help

[Randallw]

Thanks for all the help though I can't appear to fix the problem. I installed the MS antispyware program and it found a few things, also it blocks the same stuff as Venus spytrap. Anyway I'm afraid I don't understand how to stop messenger. When I installed MS antispyware there was some sort of messenger service that I stopped (not MSmessenger)and until I can work out that bit I'm not sure if it will be worthwhile replacing the hosts file as something seems to keep trying to change it which I can't find. As for my AntiVirus, I use Pccillin by Trend micro which updates a few times a day. I trust it but on this occasion what happened was that someone, who should have known better (not me), downloaded and opened something without thinking that it was malicious

Edit: incidentally, if it's any help I know exactly exactly what time it happened as I was walking past and shouted "What the hell did you do". I can search for files created at that time but don't know what to do with them.