Make backup of clients archive. If the rebuild is successful, exit GW5 and restart.
Worse case is archive is damaged and inaccessible.
If this is the case, rename or delete archive and let GW create a new one. If it does not archive, this is the source of your problem. Delete the message, exit GW5 and restart. You should back up the archive directory prior to using this utility. Only Client Services Techs will have access to this utility.