Is this with many websites, some, a few?

Many site issues can be caused by corrupt cookies or cache.

Warning ! ! This will log you out of sites you're logged in to. You may also lose any settings for that website.

• Cookies; Delete cookies to remove the information websites have stored on your computer {web link}

• Cache; How to clear the Firefox cache {web link}

If there is still a problem, Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Did this help?

While you are in safe mode;

Try disabling graphics hardware acceleration in Firefox. Since this feature was added to Firefox it has gradually improved but there are still a few glitches.

How to disable Hardware Acceleration {web link}

It happens with any website that I stay logged into, email,forums,weather and media sites. At least a dozen. When it happens I get logged out of all the sites at the same time. Hardware acceleration was turned off a long time ago. I will try the other suggestions.

Problem still exists . Tried everything suggested.

If clearing cookies didn't help then it is possible that the cookies.sqlite file that stores the cookies got corrupted.

Rename (or delete) cookies.sqlite (cookies.sqlite.old) and delete other present cookies files like cookies.sqlite-journal in the Firefox profile folder in case the file cookies.sqlite got corrupted. http://kb.mozillazine.org/Cookies

https://support.mozilla.org/kb/Deleting+cookies

Type about:support<enter> in the address bar.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the above file(s). Then rename or delete it. Restart Firefox.

If clearing cookies didn't help then It is possible that the cookies.sqlite file in the Firefox profile folder that stores the cookies got corrupted.

• rename/remove cookies.sqlite (cookies.sqlite.old) and if present delete cookies.sqlite-shm and cookies.sqlite-wal in the Firefox profile folder with Firefox closed in case cookies.sqlite got corrupted.

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Re-named the cookie file and so far so good. It's been a bit over 4 days without the issue. Thanks. Is there anything that can be done to keep the cookies file from being corrupted in the future?

Without knowing how the file was corrupted . . . .

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution more easily.

Thank you for contacting Mozilla Support.