[CentOS] Mail problems? Need help finding this process!

Hello All,

I can't get this one figured out. The few search hits I get on it 
suggest it is mail-related, but I don't even know how that was determined.

Apr 11 12:18:17 mxt root: Process did not exit cleanly, returned 255 
with signal 0

I get one of these per minute. I can't seem to tweak for more verbosity.

Could someone tell me what is going on or point me to a place to 
start troubleshooting this?

CentOS 5 final fully updated
Sendmail 8.13.8
Dovecot 1.01
MailScanner 4.68.8
SpamAssassin 3.2.4
ClamAV 0.92.1

My milters have been turned off for troubleshooting.

Thanks,
Glenn