Not sure what issue you are having, I use firefox exclusively. Check to see if you have javascript disabled or if you are running add-ons, disable them one by one to see if one of them is causing the problem.
If that doesn't do it, I would restore firefox back to the default settings, just go to the run menu:
start --> run
type: “firefox -safe-mode” the safe mode dialog box should pop up
here you can select either "disable all addons" or "reset all user preferences to firefox defaults"