Firefox

Firefox Already Running

If you get this error, it generally means firefox exited without removing it's lock files.   You can do the following to fix is s

First, make sure you're not running firefox and kill them if you have any (note, there may be other users running firefox, this is not a problem and is irrelevant to this error:

ps -x | grep -i firefox
killall firefox

Then look for any lock files and remove them.

cd $HOME
find .mozilla/firefox -name "*lock" -ls

Use the rm command to remove the files.