I have spent all week dealing with this problem and I am at my wit's end. Firefox hangs, and nothing I can do short of a computer restart will make the process close. I try closing it with the X. When the "program has stopped working" dialog comes up that doesn't work. Terminating the process in Task Manager doesn't work. Terminating it via command line (be it nicely or forcefully) also doesn't work. Then when I do restart, it tells me the profile is in use or inaccessible. But it isn't, because THERE IS NO FIREFOX PROCESS RUNNING. So I have to set up a new profile, port over profile information, and this happens again and again and again. I have tried deleting the "parent.lock" files (which has never once worked, so I'm not sure why this advice exists). I have tried not moving over the places.sqlite file. I have tried turning off hardware acceleration. I have tried uninstalling Firefox. None of it works. I can't even delete, rename or move the old profile folders because it says "they are in use" even though they are not. I have been a loyal FIrefox user since the browser came into existence, but I am about to say screw it and go back to IE or something, because this is getting ridiculous. I can't spend all day creating new Firefox profiles.