Once upon a time, I was super pro IE. After many, many viruses and browser hijacks (and popups!) I decided to give Firefox a shot. I figured, why not? It's a measily 6M download.
Wow! No popups (well, I had ONE, not sure why, but that's it) nothing installed against my will, and tabbed browsing! I thought the tabs were stupid when I first heard about it, but now that I've used it, I can't go back!
As for your problem, as mentioned earlier, delete all cache files and cookies.