The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

Thanks. I did exactly what you wrote but it did not solve the problem. I get the same error message window, "The page isn't redirecting properly

         Firefox has detected that the server is redirecting the request for this address in a way that will never complete.

 This problem can sometimes be caused by disabling or refusing to accept
   cookies."

go to accounts.google.com, log out, then go to gmail.com, and log back in.

This can be caused by corrupted cookies or cookies that aren't send or otherwise blocked.

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

Clear the cache and the cookies from sites that cause problems.

"Clear the Cache":

• Tools > Options > Advanced > Network > Cached Web Content: "Clear Now"

"Remove Cookies" from sites causing problems:

• Tools > Options > Privacy > Cookies: "Show Cookies"

• http://kb.mozillazine.org/Cookies
• https://support.mozilla.org/kb/Deleting+cookies