timeout waiting for input from local during Draining Input

I have been getting this error and messages sitting in the queue as
'Sending' on a low traffic Sendmail 8.13.1 server. From searching for an
resolution, I found this may have something to do with locking and my
global /etc/procmailrc file that contains one recipe to copy any mail to
a certain domain to a mailbox...

:0 c
* ^TO_.*domain
* !^Received:.*localhost.*cab\;
/home/sites/mail.domain.com/users/cab/mbox

I did have the lock semicolon at the end of the first line and took it
off, but still happening...

Jan 25 12:04:36 tpa-customer sendmail[30545]: m0PH2Zeo030544: timeout
waiting for input from local during Draining Input

This server also runs dovecot and I read one posting online about making
sure the lock method was equal to sendmail, fcntl. So, I updated my
/etc/dovecot.conf and restarted dovecot as well. When I stop dovecot,
all messages in the queue go out immediately and then this starts to
happen again after several minutes.

Can anyone suggest what is happening? Thanks in advance.