Here is a screenshot. Sorry for not including it in the initial post.

Hi EricMG,

  The problem is not bigger,it  like some error occur. It would not be consider ....

Try to remove the Firefox plist file (org.mozilla.firefox.plist).

• http://www.macfixit.com/article.php?story=20060606082246983 How .plist files become corrupt and troubleshooting the results

Go to "~/Library/Preferences" and remove the plist file for Firefox (org.mozilla.firefox.plist)

Note that you can't attach a screenshot to the first post that starts a thread, but you can do that in subsequent replies.

Much appreciated, cor-el, but that didn't do the trick.

You can check for problems with the sessionstore.js and sessionstore.bak files in the Firefox profile folder that store session data.

Delete the sessionstore.js file and possible sessionstore-##.js files with a number and sessionstore.bak in the Firefox profile folder.

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

Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost and you will have to recreate them (make a note or bookmark them if possible).

Create a new profile as a test to check if your current profile is causing the problems.

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 some files from an existing profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over the problem.

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

I'm seeing this as well: Firefox 26, Mac OS 10.6.8, MacBook Pro. The Window menu clears up if I quit and restart Firefox. It would seem to be related to certain privacy settings (accepting cookies or not), as described at MozillaZine.

Cor-el, the new profile suggestion was a huge help. Took a few days of testing each setting and add-on, and I was about to post my findings, but gyrofrog beat me to the post.

The problem is definitely linked to the privacy setting for cookies. If you set it to "ask me every time", whether you get a pop-up window or not, it happens.

Does anything happen if you click this empty space in the Windows menu?

It sounds that that there might be some hidden windows open asking for permission that somehow either show with an empty name or remain as ghost windows that aren't doing anything.

As far as I can tell, clicking on a "blank" item (empty space) doesn't effectively do anything -- the menu "flashes" once, like when selecting an actual window, but it (apparently) does not navigate to another window.

If it helps, I have FF set up to open windows and tabs from last time. As mentioned, when I restart FF, the empty spaces are gone from the menu. This leads me to think that they aren't "actual" windows, ghost or otherwise - at least, FF doesn't try and re-open them on restart.

I did find this bug report from 2009.

I haven't yet tried what it says (I'd like to avoid deleting anything, if I can) so I'm not sure if this is the same problem or not.

You can try to remove the Firefox plist file (org.mozilla.firefox.plist).

• http://www.macfixit.com/article.php?story=20060606082246983 How .plist files become corrupt and troubleshooting the results

Go to "~/Library/Preferences" and remove the plist file for Firefox (org.mozilla.firefox.plist)

Thanks but deleting the plist file did not help. I did notice that there were other plist files that seem to be associated with Firefox, or Mozilla in general. But I only deleted the one that you specified. Still getting the long and blank Window menu.

One thing I noticed is that deleting the plist file did not seem to affect my preferences. Everything seemed to work the way I had previously set it up. That's fine, since I was worried about losing preferences, just that I'm not sure I effectively did anything one way or the other.

P.S. Still does it after updating to Firefox 27.0.1