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Only one copy of Firefox can be open at a time
I use a mac and updated to FF 4. There were problems.
I followed a suggestion on the Mozilla support page to delete the pluginreg.dat file and restart FF4. When I did that I got the message "Close Firefox: A copy of Firefox is already open. Only one copy of Firefox can be open at a time." But there were no other copies open.
I restarted the computer and got the same error message. I reinstalled FF4 and got the same message. I don't see the file I deleted in the trash, and even if I found it I don't know what folder it should be returned to. How to I uninstall everything in FF4. Maybe I should go back to FF3?