Firefox error

Today when i installed the megaupload uploader thing (they call it the MegaManager or something), it crashed my firefox (i think <_< Didnt quite notice, but im fairly sure of that), and since then none of my addons work. I opened the addon menu, and it said firefox had to be restarted to install them. I restarted it about 5 times, closed spybot, did it again, etc and got nothing. I even upgraded to 3.0.1 (was still on 2.x something) and it wont work >_>

Any ideas? ._. I miss my adblock