cyrusdb error for long idle clients

[daniel qian | ???]

My boss likes to leave his outlook on overnight and this problem has 
been happenning to him everyday since the day I migrated to 
postfix+cyrus imap. In fact it will happen to every user if he doesn't 
close outlook when he leaves the office. The  next morning he finds  his 
outlook is not connectted to the server ( Even if I set the timeout 
parameter in imapd.conf to 24 hours). So he closes outlook and  open it 
again trying to reconnect. But nothing is his inbox. He has to retry for 
a few  minutes before he can eventually see his messages in the folders. 
This is the error messages when he trys to reconnect:

Jul 17 09:27:37 mail imapd[12947]: DBERROR: error fetching 
user.daniel.Trash: DB_RUNRECOVERY: Fatal error, run database recovery
Jul 17 09:27:37 mail imapd[12947]: DBERROR: error fetching 
user.daniel.Trash: cyrusdb error

Could anyone please advise what is going on with my cyrus imap server?

Thanks,
Daniel