Have you made sure that JavaScript is enabled? To do that in the Firefox menu select Preferences to open the preferences dialog. Go to the Content panel and make sure the setting "Enable JavaScript" is selected. If it is selected, do you have an extension such as NoScript that could be blocking scripts? If you do not have NoScript, you can check to see if an extension is blocking scripts by following the procedure in this link - https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes