My wife just turned on her computer and up popped a window stating "You need
to download XXX to clean up your computer. You have visited adult sites."
Of course we did not download.

Now a) I don't use my wifes computer, and b) I don't visit A sites.

My wife is PO'd

We run Norton AV (always up to date), Trend Micro anti spyware and
Ad-Subtract plus firewall, so I am curious, what got through and how?

What do I need to do, am running a full AV scan?

Martin