MySQL daemon won't start

Question

After years of working fine, MySQL just stopped working the other day. When I try to start mysqld manually with mysqld_safe, I get this:
Starting mysqld daemon with databases from /var/mysql
rm: /var/mysql/mysql.sock: Permission denied
STOPPING server from pid file /var/mysql/quicksilver.lan.pid
081129 12:58:11 mysqld ended
I discovered that trying to manually remove (rm) the mysql.sock file gives the same "Permission denied" error. Even though it seems like the permissions/ownership should allow it:
srwxrwxrwx 1 mysql admin 0 Nov 26 15:25 mysql.sock
Using sudo works to delete the file, but then mysqld_safe gives:
Starting mysqld daemon with databases from /var/mysql
STOPPING server from pid file /var/mysql/quicksilver.lan.pid
081129 13:34:04 mysqld ended
I note the mysql.sock file is 0 bytes: is this wrong?
I don't know what else to try.

Answer 1

Here are the permissions for the socket:
srwxrwxrwx 1 mysql admin 0 Nov 29 23:12 mysql.sock
I'm logged in as an admin, but I'm not allowed to delete the socket:
rm /var/mysql/mysql.sock
rm: /var/mysql/mysql.sock: Permission denied
(which incidentally is the message mysqld_safe prints when it tries to start)
I deleted the socket using sudo once before and it didn't change anything.
Here's the output of ls -al /var/mysql:
total 41416
drwxr-xr-x 22 mysql admin 748 Nov 29 23:12 .
drwxr-xr-x 35 root wheel 1190 Nov 29 23:05 ..
-rw-rw---- 1 mysql admin 6148 Dec 2 2004 .DS_Store
drwx------ 27 mysql admin 918 May 30 2008 MailStewardProDB
drwx------ 14 mysql admin 476 May 24 2007 SharedMedia
drwx------ 8 mysql admin 272 Aug 12 2006 drs
drwx------ 165 mysql admin 5610 Nov 8 18:38 flagNtag
drwx------ 5 mysql admin 170 Sep 13 2004 home_automation
-rw-rw---- 1 mysql admin 25088 Sep 11 2004 ibarch_log0000000000
-rw-rw---- 1 mysql admin 5242880 Nov 19 08:23 ib_logfile0
-rw-rw---- 1 mysql admin 5242880 Sep 11 2004 ib_logfile1
-rw-rw---- 1 mysql admin 10485760 Nov 19 08:23 ibdata1
-rw-rw---- 1 mysql admin 338 Dec 3 2006 localhost.err
drwxrwx--- 51 mysql admin 1734 Jul 18 2006 mysql
srwxrwxrwx 1 mysql admin 0 Nov 29 23:12 mysql.sock
drwx------ 27 mysql admin 918 Sep 10 2007 phpmyadmin
drwx------ 14 mysql admin 476 Dec 27 2007 pim
-rw-rw---- 1 mysql admin 189926 Nov 30 13:46 quicksilver.lan.err
drwx------ 14 mysql admin 476 Sep 12 2004 sg_coalition
drwx------ 6 mysql admin 204 May 9 2007 test
drwx------ 92 mysql admin 3128 Apr 6 2008 weed_bug
drwx------ 24 mysql admin 816 Aug 23 2007 x2web
I don't see any problems here.