Firefox Problem

I've noticed Firefox has always been a bit squirrelly, especially when playing streaming video or something fancy like that. It hangs and I have to force quit it. Lately it has refused to launch at all. It starts and the Icon appears in the Dock but the popup menu reads, Application Not Responding. There is no browser window up at all. I've tried removing the program and reinstalling a freshly downloaded new copy with no luck. I really like Firefox the best of all browsers. I'd be sad to have to only use Safari.

Any ideas?