I was an avid Firefox fan for sooo long!
Then it turned out to be incompatible with my college's website... So I couldn't access my school e-mail, get into my message boards, or anything else I NEEDED to have access to...
THEN I started having issues with other random sites, getting popups about script errors and all sorts of freezing issues... I couldn't use MP at ALL, because every time I got to the page I would get message after message (layering one over the top of the other until I had about 5-6 on my page) warning me of script errors. I thought I had a virus or something. The computer guy I had come check out my computer told me that Firefox has been having issues lately with certain scripts... which sucks, because I really do like Firefox...
BUT... Now I use Google Chrome, and haven't had any issues since. :)