Just downloaded the new Tor browser bundle on my MACBOOK Pro and I get a message that reads "a copy of firefox is already running. Only one copy allowed at a time." Any suggestions for newbie, like myself?
Verify, via the terminal command
ps aux | grep firefox, that no previous Firefox process was abnormally stopped and kept in 'ghost' status.
If it's the case, kill the process via
kill -9 <id> or reboot the machine and then verify again, via terminal command
ps aux, that no Firefox process is still running.