If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

• http://kb.mozillazine.org/Session_Restore
• https://support.mozilla.org/kb/Session+Restore

If it works in Firefox Safe Mode, then the problem is being caused by one of your Add-ons. You will need determine which Add-on is causing the problem. Read the following articles:

• Troubleshooting extensions and themes
• Troubleshooting plugins
• Basic Troubleshooting

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