Inform users about permission issues through FAQ
When a users extract TBB to a privileged location like %ProgramFiles% then Firefox will start up with the confusing message "Firefox is already running. (...)" The problem is not that Firefox is running, but that it cannot write a lock file. (see #4782 (moved))
We should inform users about this issue and that they should extract the bundle to a non-privileged location. This will be added in the short user manual (#5757 (closed)). But having this available in the FAQ allows us to point users to it, instead of mailing or linking tsum.