Start Firefox in Safe Mode {web link} by holding down the <Shift> (Mac=Options) key, and then starting Firefox.

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

Thank you. Problem goes away in safe mode. Now I need to find out which add on or setting is causing the problem. I will work on it.

I removed some add ons and dissabled all add ons but my session manager and the restart menu one. Problem is gone. I'll check as I add back some add ons. I'm glad it was not browser settings as I tend to only enable things that are needed by web pages I use.

Thank you.

Once you think you found the problem, disable that and re-enable all the others, then restart again. Let us know who the suspect is, detective.

Updated any add ons that needed it (many). Deleted a few. Added back add ons that I will be using now. Culprit not identified. I'll watch for the problem as I add others. I'm good for now. Sorry I can't share the specific culprit. Thank you for the help.

Glad to help. Safe Surfing.