You are using a beta version. Reinstall it. Is the problem still there?

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?

I uninstalled and reinstalled Firefox as you recommended, but it just happened again - I clicked a link on a webpage and the tab just closed.

And Safe Mode?

Next time, right click the link and use the menu.

As I said, it doesn't happen often, like, not even everyday, so working in safe mode for several days only to test whether this bug happens would be a major inconvenience.

When this occurs, does "Undo Close Tab" work or does it immediately self-close again? Undo Close Tab is available from either:

• History menu
• right-click a different tab

If the entire window closed because it only had the one tab, you'll first need to restore the closed window from the History menu. (That probably won't work in a private window.)

I haven't tried "Undo Close Tab", I'll try the next time it happens and tell you whether it works.

So far it never happened with a single tab (maybe because I rarely work with one).

It happened again (as you see, two days passed since last time). The "Undo Close Tab" works.

If you check the back history of the tab that got closed, do you notice any pattern?

The reason I ask is: pages are generally not allowed to close themselves unless they were launched from a script. If, hypothetically, a page was designed to close itself when you leave it, and Firefox is not canceling that action when you load the new page in the same tab, perhaps that could explain how it is getting closed. Otherwise, it's very hard to explain since the new page probably wouldn't want to close itself.

No, I did not notice any pattern on what gets closed, and as far as I can tell most of the websites that were closed have no ability to close themselves.

This might help; http://kb.mozillazine.org/Prevent_websites_from_disabling_new_window_features

Type about:config<enter> in the address bar. If a warning screen comes up, press the Be Careful button. At the top of the screen is a search bar. Enter dom.disable_window From this list, set everything to True.

That didn't work, it just happened again.

It seems that the problem disappeared by itself. Probably some update fixed it.

Here's hoping. Please flag your last post as Solved Problem so others will know.

...AND it's happening again :-\

Any new info on the situation, pattern, etc.?

A post was flagged as Solved Problem. Please remove that flag. If you don’t, others that can help may not read this post.

Go to that message, and use the Undo link to its right.

It's only happened a few times again, but it seems as random as it was before.