Well here's a thing!
Had a call from a colleague the other day. "Jim, my laptop's gone all funny - it's getting slower and slower, and now it won't print."
In short, I lent him a lappy and got round to his this afternoon. (had enough of hospital visiting for one week - and it's only Wed...)
Three av programs inc AVG - and Ad-aware on top of 'em... turns out it had been 'repaired' by son-in-law who 'knows about computers'.
Isolated the m/c, stripped out the lot and installed Avast! Four Trojans and five rootkits so far: I took it round to him, and left a full scan running.
I'm grateful to you lot for persuading me to instal Avast! (I had known that AVG hasn't a rootkit detector built in, and had the AVG anti-rootkit installed... but still.)