Firefox locked for one user -- How to clear?

[Scott Ledyard]

About once a week, a student approaches me and says that Firefox is
broken. When you try to run Firefox, a message comes up that says that
it's already running.  Re-logging in does not help. The end-of-day
reboot does! This was a problem in Edubuntu thin client 6.10 and now
in 7.04.

When I explore (on my on PC) the stuff in
~/.mozilla/firefox/xxxxxxxx.default (where xxxxxxxx are the 8 random
characters Firefox dreamed up when first run) I see:

redboot at dv6-Feisty:~/.mozilla/firefox/y4huipnq.default$ ls -Al
total 7312
-rw-r--r-- 1 redboot redboot     100 2007-05-08 06:18 blocklist.xml
drwx------ 2 redboot redboot    4096 2007-05-08 06:08 bookmarkbackups
-rw-r--r-- 1 redboot redboot   83958 2007-05-06 19:51 bookmarks.bak
-rw-r--r-- 1 redboot redboot   83958 2007-05-06 19:51 bookmarks.html
drwxr-xr-x 2 redboot redboot   12288 2007-05-08 06:54 Cache
-rw------- 1 redboot redboot   65536 2007-05-06 19:51 cert8.db
drwxr-xr-x 2 redboot redboot    4096 2007-04-30 20:50 chrome
-rw------- 1 redboot redboot     124 2007-04-30 20:50 compatibility.ini
-rw-r--r-- 1 redboot redboot  136697 2007-05-03 15:13 compreg.dat
-rw------- 1 redboot redboot   17522 2007-05-08 07:04 cookies.txt
-rw------- 1 redboot redboot  348259 2007-05-04 07:57 delicious.rdf
-rw-r--r-- 1 redboot redboot    7434 2007-05-05 17:39 downloads.rdf
drwxr-xr-x 4 redboot redboot    4096 2007-05-08 06:18 extensions
-rw-r--r-- 1 redboot redboot     418 2007-05-03 15:13 extensions.cache
-rw-r--r-- 1 redboot redboot     404 2007-05-03 15:13 extensions.ini
-rw-r--r-- 1 redboot redboot    7828 2007-05-03 15:13 extensions.rdf
-rw-r--r-- 1 redboot redboot   13008 2007-05-06 19:51 formhistory.dat
-rw-r--r-- 1 redboot redboot  208056 2007-05-08 06:54 history.dat
-rw------- 1 redboot redboot     128 2007-05-03 10:34 hostperm.1
-rw-r--r-- 1 redboot redboot    1667 2007-05-03 15:13 install.log
-rw------- 1 redboot redboot   16384 2007-05-06 19:51 key3.db
-rw-r--r-- 1 redboot redboot   12429 2007-05-08 06:45 localstore.rdf
lrwxrwxrwx 1 redboot redboot      18 2007-05-08 06:08 lock -> 192.168.1.10:+5932
-rw-r--r-- 1 redboot redboot    1992 2007-05-05 17:36 mimeTypes.rdf
-rw-r--r-- 1 redboot redboot       0 2007-05-08 06:08 .parentlock
-rw-r--r-- 1 redboot redboot   26409 2007-05-08 06:47 prefs.js
-rw-r--r-- 1 redboot redboot    3287 2007-04-30 20:50 search.rdf
-rw-r--r-- 1 redboot redboot    2048 2007-05-03 15:13 search.sqlite
-rw------- 1 redboot redboot   16384 2007-04-30 20:50 secmod.db
-rw------- 1 redboot redboot   25488 2007-05-08 07:01 sessionstore.js
-rw------- 1 redboot redboot     971 2007-05-08 06:38 signons2.txt
-rw-r--r-- 1 redboot redboot 2109440 2007-05-08 06:56 urlclassifier2.sqlite
-rw-r--r-- 1 redboot redboot 2250348 2007-05-03 15:13 XPC.mfasl
-rw-r--r-- 1 redboot redboot  103964 2007-05-03 15:13 xpti.dat
-rw-r--r-- 1 redboot redboot 1801727 2007-05-06 11:06 XUL.mfasl
-rw-r--r-- 1 redboot redboot   21149 2007-05-08 06:59 ybookmarks at yahoo.log

The linked file "lock" looks promising, but is that an IP:port it's
linked to?  Any clues how to unlock this user?