Firefox can't remember to block pop-ups.

I’m having the oddest issue with my browser. I can turn the pop-up blocker on, and it’ll stay on until I exit out. The next time I restart, it’s disabled. I had this problem with Firefox 2, and while I was hoping that upgrading to Firefox 3 would fix it, it didn’t. Any ideas?

They suggest you uninstall 2 before installing 3. Maybe that’s the problem?

I’d be more inclined to believe that if the problem hadn’t already existed before I upgraded.