Working on this at present. We had a crash - not quite sure what cause the crash at the moment, but the crash corrupted the database. How badly is yet to be discovered...
I've fixed the obvious problems and rebooted the server. Taking some backups before we go any further. However, if the database is hosed, we have a two day-old backup that I know is okay, so we won't lose much. Hopefully that won't be necessary - if I can get the db cleaned up again we shouldn't lose anything.
Will report more once I've got a bit further.