Chatrooms and conversations disappearing following db restore

We have a regular requirement to restore Openfire to a previously backed-up state. Its Openfire 3.6.4 on Windows Server 2003, database on separate virtual server running W2K3 and SQL Server 2005.

The cycle is…

Backup: Stop Openfire Windows service; Back-up database via standard SQL Server tools; Restart Openfire service

Restore: Stop Openfire service; Restore db via SQL tools; Restart service

This seems to work fine where the restore occurs soon after back-up (as would happen in development environment!) But if the back-up is more than a day or so old, conversations are lost, older again and seems the chatrooms disappear as well.

When the backup and restore are performed on different systems (but where the systems consist of cloned virtual servers), the data is missing on the target system following restore but not on the source system at the same time - suggests there’s no chat data ‘expiry’ taking place.

Haven’t been able to fine any explanation via forum searches etc. Grateful for any advice - Thanks.