• Disable a possible RealPlayer Browser Record Plugin extension for Firefox and update the RealPlayer if installed
• Disable protected mode in Flash 11.3 and later
• Disable hardware acceleration in the Flash plugin

• http://kb.mozillazine.org/Flash#Flash_Player_11.3_Protected_Mode_-_Windows

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.

You can check for problems with the places.sqlite database file in the Firefox Profile Folder that stores the history and the bookmarks.

• http://kb.mozillazine.org/Bookmarks_history_and_toolbar_buttons_not_working_-_Firefox
• https://support.mozilla.org/kb/Bookmarks+not+saved#w_fix-the-bookmarks-file

When i switch to safe mode everything works fine. But how do i know which plugin to disable to make it work again?

• Remove unwanted addons
• updated your plugins
• use default Firefox theme

In order to uninstall a possibly unwanted extension, please do the following:

1. From the Firefox window click the Firefox button at the top left and select Add-ons, or, if the Firefox button is not shown, click the Tools menu and click Add-ons.
2. Once the Add-on Manager has opened in a new tab, click the Extensions button on the left side of the window.
3. You should now see a list of your installed extensions on the right side together with buttons on the right side of each extension.
4. To remove an extension from Firefox, simply click the Remove button. You should see a message that informs you about the successful removal of the add-on.
5. Note that some add-ons require a Firefox restart to be removed completely. To perform a Firefox restart after the add-on removal, click the Restart now link in the message.

You can find further information about uninstalling extensions in the following articles:

Disable or remove Add-ons

Remove a toolbar that has taken over your Firefox search or home page

Thanks!

Suggestions does not work for me (Including safe mode). When I tried to enter Outlook, it always becomes "not responding" (outlook is just the most obvious example, there are many sites similar to). I have this problem for almost a year. Tried all the support documentations and suggestions in the forums, but the result is zero. Therefore, Firefox lost a lot of blood but it seems they don't give enough priority to these issues. I love Firefox but I don't have the patience anymore.

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 careful not to copy corrupted files.

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

Try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that helps.