Try the F12, so its back to normal mode from full scree mode

You can check for problems caused by a corrupted localstore.rdf file.

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

(F11 toggles full screen mode)

Thank you so much! You're the man! I did correct the screen view/window size, apparently by installing a fresh version (26 I think) of FIrefox. I now have another situation, namely that (1) the browser reverts to the web page previously viewed, after FIrefox is closed, and then reopened. Cannot understand why? (2) When I've opened more than one web page, or several tabs, at one time, and then close Firefox, the browser will not re-launch or open in a new start page. I get a notice "FIrefox is still running. You must either close it or re-start your computer." This has been going on actually for some time. I also get "Que error" messages, when the browser is "stuck" and will not re open. Any ideas?

You can check if you have an user.js file in the Firefox profile folder that sets the browser.sessionstore.resume_session_once pref to true.

• http://kb.mozillazine.org/browser.sessionstore.resume_session_once

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

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

See also:

• http://kb.mozillazine.org/Preferences_not_saved