I was perhaps a little extreme in my earlier note, but I'd just had a bad flight through some websites that inundated me with pop-ups. I'm sure there are some useful purposes to which they can be put, but I haven't encountered those.
I'm not able to sleuth out all the details right now, but there is software that can block pop-ups. Play with
www.Komando.com ,
www.getprivatenow.com, and
www.anonymizer.com , if you keep having trouble.