error fetching txn cyrusdb error

[brian]

Using 2.2.13

I'm seeing a lot of the following in my mail log:

cyrus/imap[50924]: IOERROR: locking 
/var/lib/cyrus/domain/q/DOMAIN.org/user/a/admin.seen: Interrupted system 
call
cyrus/imap[50924]: DBERROR: error fetching txn cyrusdb error
cyrus/imap[50924]: Fatal error: Internal error: assertion failed: 
seen_db.c: 275: seendb && seendb->uniqueid

[...]

cyrus/lmtpunix[11672]: IOERROR: locking header for 
DOMAIN.org!user.admin: Interrupted system call

[...]

cyrus/master[13921]: can't fork process to run event checkpoint
postfix/smtpd[5224]: fatal: file /etc/postfix/main.cf: parameter 
default_privs: unknown user name value: nobody
cyrus/deliver[4091]: connect(/var/run/cyrus/socket/lmtp) failed: No such 
file or directory
cyrus/deliver[11366]: connect(/var/run/cyrus/socket/lmtp) failed: No 
such file or directory
cyrus/deliver[23725]: connect(/var/run/cyrus/socket/lmtp) failed: No 
such file or directory
cyrus/deliver[8044]: connect(/var/run/cyrus/socket/lmtp) failed: No such 
file or directory
cyrus/deliver[13884]: connect(/var/run/cyrus/socket/lmtp) failed: No 
such file or directory
cyrus/deliver[16162]: connect(/var/run/cyrus/socket/lmtp) failed: No 
such file or directory
cyrus/deliver[28191]: connect(/var/run/cyrus/socket/lmtp) failed: No 
such file or directory

[...]

cyrus/imap[28407]: IOERROR: locking 
/var/lib/cyrus/domain/a/DOMAIN.com/user/a/andrew.seen: Interrupted 
system call
cyrus/imap[28407]: DBERROR: error fetching txn cyrusdb error
cyrus/master[15510]: process 28407 exited, signaled to death by 6
cyrus/lmtpunix[7938]: IOERROR: locking header for DOMAIN.org!user.admin: 
Interrupted system call
cyrus/lmtpunix[30354]: IOERROR: locking header for 
DOMAIN.org!user.admin: Interrupted system call

Some of these appear to be related, although not all. The 
IOERROR/DBERROR lines suggest to me that I may need to run reconstruct 
on the mailboxes. Does that seem likely? Filesystem problems?

The cyrus/deliver errors are odd. I don't have a directory at:
/var/run/cyrus

Although I do have:

/var/run/cyrus-master.pid

In Postfix's master.cf:
cyrus-deliver unix  -       n       n       -       -       pipe
   user=cyrus argv=/usr/lib/cyrus-imapd/deliver -e -r ${sender} -m 
${extension} $recipient

Any ideas?