Disable the "AVG Safe" extension if you have it. See if it works then.

If it does you can leave it disabled, uninstall it, or make sure you have the latest AVG Free version which is supposed to work with Firefox 6.0. But they've been wrong about that a few times.

Uninstall instructions can be found in "Problematic extensions:" http://kb.mozillazine.org/Problematic_extensions

If that's not the problem there is a link at the top of the page to help you narrow down the extensions.

Thanks for the reply but I do not have that extension.

Start Firefox in Use Troubleshoot Mode in Firefox to check if one of the extensions 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

If it works in safe mode you then it is an extension to narrow down which extension see http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Extension_issues

Thanks guys. Only 3 extensions enabled. Disabled each one by one... no change. Do these rules apply to Plug-ins as well?

Try to open a new window and see if that gives a working location bar.
If that new window works then close the not working window.
It may have been caused by visiting a website that disabled some windows features and make the location bar read-only.

• http://kb.mozillazine.org/Prevent_websites_from_disabling_new_window_features
• http://kb.mozillazine.org/JavaScript#Advanced_JavaScript_settings

By the way, since this problem started, every time I open Firefox at least six or seven different windows open; some blank, some with last sites visited! Maybe I need to reinstall the whole shebang?

It is possible that there is a problem with the files sessionstore.js and sessionstore.bak in the Firefox Profile Folder.

Delete the files sessionstore.js [2] and sessionstore.bak in the Firefox Profile Folder.

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

If you see files sessionstore-##.js with a number in the left part of the name like sessionstore-1.js then delete those as well.
Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost, so you will have to create them again (make a note or bookmark them).

See also:

• [1] http://kb.mozillazine.org/Session_Restore
• [2] http://kb.mozillazine.org/sessionstore.js

Thanks for all of your help. The problems seem to have resolved themselves.