Start Firefox in [[Safe Mode]] to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Themes). * Don't make any changes on the Safe mode start window. See: * [[Troubleshooting extensions and themes]] ---- Create a new profile as a test to check if your current profile is causing the problems.<br /> See [[Basic Troubleshooting#Make_a_new_profile|Basic Troubleshooting&#58; Make a new profile]]<br /> There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins"<br /> If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files) See http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox