Thunderbird Stalled

[Jonathan Allen]

Hi List,

We have a machine running FC6, using thunderbird as the MTA.  For some
reason the machine crashed while thunderbird was being used by a user.
Although the machine has been rebooted several times, the contents of
/tmp completely removed and the user logged back in and out again several
times, thunderbird now refuses to start, claiming that another instance
of thunderbird is already running.  Running ps -aux | sort | more reveals
no such process, unsurprisingly, so there must be some lock file or
process-id file somewhere within the user's filestore or home directory
space that is causing the problem.

Can anyone help me to unlock this unhappy user and tell me which file
to pull so that they can get on with their email ?

Jonathan