My Firefox browser has a nasty habit of freezing while I’m working, requiring a reboot to get it working again. Can you tell me why it does this?
I'm curious too, as to what operating system you are currently using. Tina is on the right track here... Also, If this happened recently, it could be due to the fact that Firefox also just released a new version "Firefox 5." And downloads are supposed to become mandatory in the coming days.... Maybe try giving it a manual update too, couldn't hurt.
Also, firefox is/has been known to use TREMENDOUS amounts of "system resources" on windows machines. Many have tried to put their finger on exactly "why" this is happening, but the only "educated" guess that I've heard in the past is that "Firefox Plug-ins / additional installs" are usually the main cause of this "freezing" problem. Next time your browser freezes, if you can "CTRL+ALT+DEL" and get to your active processes, see if its your "plugin-container.exe" that is hanging it up... That would backup the Firefox "plug-in" theory, if it's simply Firefox that's hanging up and using (over a gig of system mem typically), then I have a good idea that its probably your OS or your version of Firefox conflicting with something on your machine...
One last thing, I'd also try a "fresh restore" on Firefox, by going to Firefox at the top left and clicking options, then do a "total restore" (can't remember the exact tab), but it will at least restore Firefox to it's original settings.
what operating system and version and what version of Firefox are you running?
Does it freeze randomly or could you recognize a trigger, for example multiple tabs open or multiple programs open etc?
To fix it you would also try to create a new Firefox profile and see whether the crashes happen due to problems with browser extensions.