Hi Matt

I am not a Mac user, but that obviously should not happen.

Does it help if you give Firefox longer to closedown, at least 10 minutes before trying to kill it or power off. Longer if you clearly see disk activity associated with Firefox after you commence the tying to exit Firefox.

If Firefox has issues trying to close down it should time out, and then start to try to generate and file a crash report. It would be worth looking in about:crashes to see if you have any recent submitted crash reports

• Firefox crashes - asking for support <-- but post the crash IDs beginning with bp- as a reply to this post

If you have problems closingdown Firefox it is normal for the next restart to take longer than usual, sometimes a lot longer. This is because Firefox may need to do additional tasks at start up after a closedown ended unexpectedly.

It would be worth doing a clean reinstall of Firefox. That involves deleting the program files, NOT the profile files.

• Firefox keeps crashing at startup_try-a-clean-install

Just a longshot: Have you set Firefox to forget History when it closes ? If so try a couple of consecutive closedown and restart cycles with Firefox set to the default remember History

• Does that help ?
• See Settings for privacy, browsing history and do-not-track_remember-history

Also note use of Trusteer Rapport software may sometimes be connected with this sort of symptom. If so disable or remove such software until it is updated to work with Firefox.

What is funny is that I couldn't use Safari to login and comment on the mozilla support site. It doesn't appear to work. Its one thing after another.

Interesting what you mention about Trusteer as that is installed. Its not clearly obvious how to uninstall though.

On a mac there isn't a hard drive light, ideally I would have opened the activity monitor first before trying to quit firefox. Let me be clear I'm not a heavy user of Firefox - its mainly for testing so the browser has very little in terms of extensions and plugins. And i removed the theme too. I could reinstall but it seems unncecessary given the amount of use its had so far.

History is set like most things as default settings so far.

I will monitor it over the coming days to see if the fail to close happens again.

Thanks for the reply though.

Thanks for your report! You're not alone as others have seen this issue too.

It goes without saying this is a really bad issue. Never have I ever seen a program resist being force closed/quit on any OS. Except for those malwares over the years that had that ability. In those cases you had to use the Unlocker program to end task it. But also stopping the OS from shutting down is unheard of to me.

Please monitor this bug for more info: Bug 1258515 - After Firefox update, Macbook won't shutdown

They may ask your for help to debug the issue so they will appreciate it if you can provide anything they may need to investigate this.