Created attachment 397427 [details]
Close Firefox dialog box
One window that can appear on start up is the "Close Firefox" dialog. Things we can do to avoid this dialog (that are more advanced then giving the user a problem and a list of instructions) are:
1) wait a second or so and see if Firefox has closed, often Firefox was in the process of shutting down and the user decided to reopen it.
2) actually kill the process ourselves, it's unreasonable to expect the user to know how to kill an hung process.
See also bug 295693.
I think it is important that any automatic actions (even waiting) are visible so that the user knows what the problem is and take measures to avoid this in the future if possible.
FWIW, the "kill the process ourselves" solution is covered by bug 286355 (on Windows) and is probably technically infeasible.
*** This bug has been marked as a duplicate of bug 401301 ***