10.3.9 cyrusdb error

Hi all,
I have always been able to recover my mail database using the cyrus reconstruct i command but recently I have been getting an error in my mail logs that reconstruct no longer appears to resolve:

server ctl_cyrusdb[807]: DBERROR: archive /var/imap/db: cyrusdb error

Is there any furher procedure I can enact to sort this problem out? It has been occurring for some weeks now and at first didn’t seem to be causing problems but in the last few days users are reporting disappearing emails and internal mails often don’t arrive.

I am running 10.3.9 server with all updates to around June 2006
G4 XServe.

Any help would be very much appreciated.
Thanks.