Update your Firefox to latest version of Firefox

• www.mozilla.org

Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• You can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.
• Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

Hi iamjayakumars, Thanks for taking the trouble to help here. I' m afraid FF safe mode didn't help, nor has FF updating. The issue is still there.. In updating details it says that I have FF version 11.0 since two days, but "about FF" still shows version 10.0.2  !! Still waiting for the magic solution..

If there are problems with updating then do a clean reinstall and delete the Firefox program folder before reinstalling a fresh copy of Firefox.

Download a fresh Firefox copy and save the file to the desktop.

• Firefox 19.0.x: http://www.mozilla.org/en-US/firefox/all.html

Uninstall your current Firefox version, if possible, to cleanup the Windows registry and settings in security software.

• Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you will also lose your personal data like bookmarks and passwords from profiles of other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

Your bookmarks and other profile data are stored in the Firefox Profile Folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

Hi cor-el, I followed your indications. I have made a clean reinstall of FF and deleted its program folder before reinstalling a fresh copy. Now I have FF version 20.0. Beautiful! But... the problem is still persisting. A reminding of the problem, I can't sign out of my yahoo account using the "sign out" icon (actually it is the sign out button in the FF bookmark toolbar). The resulting yahoo page shows the image attached. I can still use the sign out button in the yahoo program. Any solutions ? It seems that it isnt only a FF problem. It happens in IE8 also. So does that mean that it has nothing to do with FF ?

If you have bookmarked a specific link to log out and that link is no longer working the you need to delete this link. There is no guarantee that such a specific link keeps working and in such a case you need to abandon it and see if you can come up with a new link, but best is always to use a button or link on the website to log out.

Well that bookmark was showing on the FF bookmark toolbar from day one after installing FF. It seems to have been "inherited" from the IE (you can see it in the screenshot I sent). It was right in front of you and useful since you don't have to bother to look for the yahoo sign out link which sometimes needed to load to show. And it seems that there were I don' t what bugs or glitches in yahoo itself or my pc that the link disappears after having showed. So the one on the bookmark was excellent and sure & spared all the trouble. But well since it stopped serving its goal one has to delete it. Thanks for your help and support.