[Dovecot] Signal 11 on deliver

[Matt]

I just installed Postfix, MySQL, and Dovecot.  Everything is working
great (IMAP, POP, SMTP) except that I can't get incoming mail to
deliver properly.  Incoming mail logs the following:

Feb  2 13:23:52 mail postfix/qmgr[2187]: CE0D41F0263:
from=<mhoppes@[redacted]>, size=650, nrcpt=1 (queue active)
Feb  2 13:23:52 mail postfix/pipe[3594]: CE0D41F0263:
to=<mhoppes@[redacted]>, relay=dovecot, delay=0.32,
delays=0.3/0/0/0.01, dsn=5.3.0, status=bounced (Command died with
signal 11: "/usr/libexec/dovecot/deliver")


Running /usr/libexec/dovecot/deliver -d mhoppes@[redacted]

results in an e-mail being delivered to the recipient.

Any thoughts on what my issue is?