Just thought I would leave this here. Recently Firefox has gotten slow to the point that I had stopped logging on to NS. Firefox kept crashing and in was screwing up other programs as well. Finally I found this:
http://www.crystalidea.com/speedyfox
It fixed the problem for me. Also went onto Mozilla plugin checker and made sure that I had the latest versions:
http://www.mozilla.org/en-US/plugincheck/
I found the info on this forum.
http://support.mozilla.com/en-US/questions/884462
Anyway, this was driving me nuts and now it is tons better. Hope it helps others with the same problem.