Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• Open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you exit Firefox, do you click the X on the window or the File > Exit button?

Exiting using the File > Exit button will allow Firefox to close completely and correctly and will give it time to delete history.

I have this problem in FF 24 also, and had it in 23, 22, 21...FF repeatedly hangs and will. not. clear. history. I want the auto-fill feature cleared so I stop getting all the spam websites intruding when I type in URLs when I can't remember the whole thing - especially rental car agencies, all the shopping websites, etc etc etc. I type in a couple of letters and a huge list of stuff appears that I don't want, all these sites my wife visits. Even though none of the stuff appears in History after repeated clearings of everything, there it is in the URL. Making me crazy.

@ roughbeast

If you are still experiencing issues after trying all of the steps listing in this thread, please consider creating a new thread with the specifics of your issue.

If you don't, you most likely won't get anymore answers on this thread because this thread has been marked as solved and no longer appears on our unsolved questions list.

Thank you.

Thanks, Whiz - i didn't notice how old this thread was. So I began to post a new question, which turned up possible solutions before posting. And I found a solution partly on my own! (Safe mode didn't work - problem remained even with all plug-ins disabled.) Somebody advised deleting Places from the Profile folder, but the person asking the question said it didn't work because the Places were "in use by another program." So I dragged the Places to the trash, Quit FF, then emptied the trash. Voila! Posted my reply there, too - but then saw the thread was from July. Oh well...but thanks again.

@roughbeast

We are glad to here that you have found the solution to your problem.

Thank you for using the Mozilla support forum.