Try to rename/remove the xulstore.json file in the Firefox profile folder.

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

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

Create a new profile to test if your current profile is causing the problem.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

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

Try yo create a new Firefox desktop shortcut via the Firefox.exe file in the Firefox program folder.

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

Hmm, I've never had that problem with Firefox on any version of Windows, so hopefully one of the above suggestions will put you on course to fix it on your system.

Sometimes shutting down Windows and starting it up again will fix odd "silent breakage" issues so if you haven't tried that since this problem started, you might want to give it a shot.

Hi all,

Thanks for all the suggestions. I have just this morning had time to look at them.

The shutting down Windows and starting up again, I have tried before and that didn't work.

I had tried restarting Firefox in Safe Mode and that also did not work.

I was about to try the Profile solution, but thought I would make sure the problem still exists before doing that, and of course, it is working fine this morning. It has done that before, where, since this started, on occasion, it seemed to work properly, but then the problem reoccurred, out of nowhere.

So, I'll see how it goes, and if the problem arises again, I will try out the Profile solution.

Thanks again for the responses! MK

Went away from the computer for a bit, came back and tried to continue my excel file and using Firefox, and it has gone back to the same issue again of Firefox 'always' being on top when doing the Alt-Tab.

So I set a new profile as was suggested and the problem persisted. I've retried the Safe Mode solution and shutting down and starting up and none of these solved the problem.

This morning, all I had to do was Alt-Tab once and I could go from my excel file to the Firefox site I was using.

Now, I have to Alt-Tab to the desktop, stop, then Alt-Tab to my excel file and that worked. But then to get to the Firefox site I was using, I have to Alt-Tab again and run through the 3 choices to get there. It's not the simple Alt-Tab once that I had this morning.

And between the time this morning that it was working properly until the time I started using the computer again when it did not work properly (maybe an hour later), I did not touch the computer at all.

I don't think ordinary web pages can command a browser window to become "modal" and keep the focus on itself if you try switching applications. Perhaps it is possible if the page is using a plugin... do you have this issue with even simple pages that do not use any plugins?

Hi again, Thank you for your help and suggestions. I ran my antivirus program and 2 malware programs. The antivirus program did find 1 virus and quarantined it, but the malware programs did not find any problems. I then disabled all the plugins for Firefox, and went to a completely other site to do something else, and my browser froze up several times. I had to do the Ctl-Alt-Del things a few times, but that same thing occurred several more times, so I completely uninstalled Firefox and continued to use IE until the pages bogged down so much (the reason I went to Firefox in the first place), I had to finally reinstall Firefox. I immediately added all the plugins I had previously, Silverlight, the FlashPlayer, etc., and the Add-ons: Free Memory, Free Memory 2, Free Memory Button, Memory Restart, and Ramback, and right from the start, Firefox was working fine. I can use the Alt-Tab to go back and forth between the browser and Excel easily, and everything is working fast and smooth, even better than before the problems started. I can't explain what fixed it, because I have no idea. Maybe the uninstall & reinstall, maybe the virus that was found, I wish I knew, so I could leave a solution here for anyone else that ever runs into the problem. Hopefully, it won't be a problem again, but as of new, it's solved. Thanks for all the suggestions! Mike