@pitklad: I (think) I tried that, but I couldn't find any way to shut the scan off so it only happened on demand. Like I said, I shut down my PC overnight. I want to be able to scan on demand, not always daily.

Also I want something that will lurk in the background and keep a watchful eye out for new files arriving...

I have just (due to previous posts) downloaded and installed AVAST. Seems to be working OK so far. (I've just quarantined 3 "Ad-ware" files that AVG didn't pick up on. OK, they're not "viruses", but it's nice to get rid of them...)

And, yes, I do have "Ad-aware" and run it regularly..

But thanks for all the replies. Much appreciated!

Cheers,
Diolma