hmm...that's weird, I've been gettin em too. As soon as the forum page loaded I got this popup window ...
http://www.speedyclick.com/perl/myprepopjaguar.cgi?adcode=zct1109335oct9
... maybe it's related to Netscape cause the title says "Netscape: Pop up"
If you click it off the screen you just get another one in it's place.