Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox (Tools) > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.com/kb/Safe+Mode

• https://support.mozilla.com/kb/Troubleshooting+extensions+and+themes

I tried this. Did not work. It still locks up in Full Screen view. In fact it is locked that way right now and I will only be able to escape by ctrl. alt, delete and open the task manager to close Mozilla Firefox. I really would like it to STOP freezing so my tabs drop down when prompted. This only began with the installation of the Firefox 9 upgrade. NEVER had this problem before this. Any help would be welcome.

Can you toggle full screen mode with the F11 key?

Do you at least see the Tab bar and the Navigation Toolbar if you disable the toolbar autohide by setting the browser.fullscreen.autohide pref to false on the about:config page?

• http://kb.mozillazine.org/about:config

You can also try to delete the localstore.rdf file in the Firefox Profile Folder while Firefox is closed.

• http://kb.mozillazine.org/Profile_folder_-_Firefox

• http://kb.mozillazine.org/localstore.rdf
• http://kb.mozillazine.org/Corrupt_localstore.rdf

You can use this button to go to the Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder

Thank you for this information. I will try all of the above, and see if it unlocks with the F11 key when it freezes next time. I will let you know how it goes!

Hi RAIP27, if you have no problem, can you provide an acreenshot of your recent problem . it can be helpful for me, please try to send.

I will try. I have two screen shots-one where it is frozen and tabs won't drop. 2nd shows normal view of tab drop down when its working right.

Do a clean (re)install and delete the Firefox program folder (C:\Program Files\Mozilla Firefox\).

Download a fresh Firefox copy and save the file to the desktop.

• Firefox 9.0.x: http://www.mozilla.org/en-US/firefox/all.html

Uninstall your current Firefox version, if possible.

• Do NOT remove personal data when you uninstall the current version or you lose your bookmarks and other data in the profile folder.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

Your bookmarks and other profile data are stored elsewhere in the Firefox Profile Folder and won't be affected by a reinstall, but make sure that you do not select to remove personal data if you uninstall Firefox.

If there are still problems then try a new profile as well.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall