I wouldn't know how to create that problem. Here is my suggestion to help resolve the problem.

1. Find out if an extension is at fault by bringing up Firefox in "Safe mode" which you can do with

   "Alt+H" > "Restart with add-ons disabled..."

   Do NOT click on any of the check boxes, to do so would not be safe.

2. If you still have the problem in Safe Mode then I have no idea; otherwise ..
3. Restart Firefox so you are no longer in Safe Mode
4. Type "about:support" into the location bar so you can see what extensions (and options) you have.
5. Use Find ("Ctrl+F") to find extensions that have "Tab" in their names, and disable those as I would expect one of those extensions to be the problem so that would be the first group tested.
6. Proceed to find out which extension by suggestions outlined to enable or disable half of extension in a group of those last previously enabled/disabled or not yet disabled depending on results as outlined in
   http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Extension_issues

Meanwhile must be very difficult for you having to use

• Ctrl+(1-9) for a tab 1 through 8, or the last tab
• Tab drop-down list at the right end of tabs bar
• Ctrl+Tab keys or Ctr+Shift+Tab to go to next tab or previous tab

Were your tabs set up before to close a tab by double-click with an extension.

Thanks for the suggestions, tried all, but problem still occurs while in Safe Mode. It works OK for a while, having opened just a few tabs, but then, especially after having viewed video or switched back and forth between tabs for a while, i happens again...Have just received new laptop and do not have many extentions or plugins installed. Will continue to search for solutions.

Tabs act like they are being double-clicked and close.

Mouse problem with optical sensor.

I had that problem where clicking on a tab closed it today and the problem was the mouse. It has happened before with a small hair near the sensor. This time whatever was there was so small it looked like a scratch but it got removed and is working again.

Since I only used it while wireless mouse was charging it was a little more obvious than it would have been otherwise.

discovered the same on friday, when other programs also started to act weird, I checked the functionality for the system and discoverede tha my mouse had some sort of "short circuit" that made it some sometimes doubleclick and sometimes lag. New mouse, problem solved...