Personally, I'm a big Firefox fan. I think the best situation for us to be in as web users would be if IE loses its dominance, but no browser takes it place. THAT is how the internet should be. While...

Can't you just install a new copy overtop? This has fixed a lot of my IE problems.

Which browser, out of these two, do you think is better, and why?

What is the URL of the page being opened? Is is about:blank? Is it your homepage? Is it a file on your computer?

I use Firefox's built-in popup blocker, and it handled everything perfectly. It blocked everything it should have and didn't block anything it shouldn't have.