squid dead but pid file exists problem

hi to all,

i am running squid on FC4, lately i have this problem.

[root@gateway run]# cat squid.pid
4679

[root@gateway run]# /sbin/service squid start
Starting squid: [FAILED]

[root@gateway run]# cat squid.pid
4679

[root@gateway run]# /sbin/service squid status
squid dead but pid file exists
squid: ERROR: Could not read pid file
/var/run/squid.pid: (13) Permission denied
[root@gateway run]#

what causes this to happen? what should i do with this squid.pid?
how this process ID (pid) file been created?

pls enlighten me.

tnx

is it related to downloading? i downloaded debian ISO and left it overnight because of the time it took to download, it passes through the squid. the download was successful.

might be with caching?

pardon me but just recalling the latest activities before this squid problem occured.