As near as I can tell, it was while I was doing research, dropping into links from a google search, and hit a page that was no longer what it claimed to be (it looked like the original domain holder may have lost/given up the site, and it was taken over by opportunists). It was probably a Javascript initiated exploit (which I try to always cancel out of), but perhaps it wasn't a real Javascript warning, and the close box was mapped to the same code as the okay button. As I say, I don't know for sure, I just know roughly when it happened, and took immediate steps to fix it.

I sure wish the big boys would get involved and put out spyware removal tools of the same caliber as antivirus. I appreciate the fact that AdAware and Spybot are major efforts for very little remuneration, but this problem needs a serious infusion of cash, and only fully commercial apps are going to get it. And I still haven't found anything (even for money) that gets the job done 98% of the time. And I've got numerous clients with teenage children using the computer that desperately need a solution on the scale of antivirus protection.