User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.3) Gecko/2008092417 Firefox/3.0.3 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.0.3) Gecko/2008092417 Firefox/3.0.3 Currently, if you close Firefox and try to open back up right away, if frequently complains that it is already running. Firefox should instead present a dialog asking the user to wait until the process can be relaunched, and provide a "Force Restart" button after 5-10 seconds which will kill the previous FF process and start the new one. Reproducible: Always Steps to Reproduce: 1. 2. 3.

I think this is a duplicate of Bug 407981, Bug 452487 or Bug 399108. I believe there are also others.

Um, is this happening every time you close Firefox? If so, you have another problem. Occasionally it will leave the process running, but it should not be doing that every time. Make sure to check with a new profile.

No, not every time. Usually only after I have left FF open for a long time then close and reopen right away.

Ok then, is this the same as any of the bugs in comment #1?

yes.