I have very strange problem with firfox when every i try to download something from anywhere it crash and it show me this mess any help will make my day.This problem started few days back :confused:
http://i34.tinypic.com/24q8olu.png

try to update ur firefox or work @ firefox safemode , Start>Programs>Mozilla Firefox

Have you tried reinstalling firefox?

scan for virus and trojans also...

old problem ..might solved