[Dovecot] 1.0.1: corrupt index on fresh mailbox, ideas?

[Troy Engel]

A new employee started today, when logging into his new mailbox this 
morning during a walk-through I got a nasty server error response in 
Thunderbird - something I never see, DC runs smooth as butter for us. 
Checking the server log I see this:

== snip ==
dovecot: Jul 09 09:38:54 Error: IMAP(xxxxxxx): Maildir 
/home/x/xxxxxxx/Maildir sync: UIDVALIDITY changed (1183406107 -> 1183999134)

dovecot: Jul 09 09:39:06 Error: IMAP(xxxxxxx): Corrupted transaction log 
file /var/spool/dovecot/indexes/x/xxxxxxx/.INBOX/dovecot.index.log.2: 
invalid indexid (1183406107 != 1183999146)

dovecot: Jul 09 09:39:06 Error: IMAP(xxxxxxx): Corrupted index cache 
file /var/spool/dovecot/indexes/x/xxxxxxx/.INBOX/dovecot.index.cache: 
indexid changed
== snip ==

Some facts that make this a strange occurrence:

1) new IMAP mailbox, only one email was in it that I had sent last week 
(boilerplate Welcome email)

2) was working perfectly fine on Friday when I set things up 
(Thunderbird and SquirrelMail) and tested with the same client laptop 
and same Thunderbird

3) nothing bad happened with the servers over the weekend, all is 
tip-top - no restarts, reboots, nothing.

4) DC does use NFS mounted maildirs, but there is only one DC accessing 
any maildir - no other servers touch ~/Maildir/. mmap is disabled.

What could be a reason for this index to have gotten corrupted? This is 
the first time I've had an index go corrupt out of all the users, so I'd 
like to try and track down the cause of this...

thx,
-te

== dovecot -n ==
# 1.0.1: /etc/dovecot.conf
log_path: /var/log/dovecot.log
protocols: imap imaps
listen: *
ssl_cert_file: /opt/SSL/server.pem
ssl_key_file: /opt/SSL/server.pem
login_dir: /var/run/dovecot/login
login_executable: /usr/libexec/dovecot/imap-login
login_process_per_connection: no
mail_location: maildir:~/Maildir:INDEX=/var/spool/dovecot/indexes/%1u/%u
mmap_disable: yes
namespace:
   type: private
   separator: .
   prefix: INBOX.
   inbox: yes
auth default:
   cache_size: 4096
   cache_ttl: 7200
   passdb:
     driver: pam
     args: cache_key=%u dovecot
   userdb:
     driver: passwd
     args: blocking=yes
== end ==

-- 
Troy Engel | Systems Engineer
Fluid, Inc | http://www.fluid.com