Cannot install any Firefox updates without a clean reinstall

I cannot install any updates. Whenever I install them, I get the message "There are multiple copies of FF running, close them and try again". I've been getting this error message all the way since Firefox 2 and the only way I can install these updates are to go to getfirefox.com and install everything from scratch. I used opie, febe, and something else to export all my settings onto a different computer and the problem carried over to my other computer (or it could have started when I did it, I don't remember). I even tried uninstalling firefox and deleted ALL my preferences and doing a fresh clean install but no luck. BTW I know for a fact that there is only one copy of firefox running. Here is a video of my troubles:


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