Are you seeing any other messages, or is there more to that message?
Some suggested information..
Repairing a Database with phpMyAdmin Link goes to Google
Automatic Database Optimizing Link goes to the Codex “Please Note: That this define enables the functionality, The user does not need to be logged in to access this functionality when this define is set. This is because its main intent is to repair a corrupted database, Users can often not login when the database is corrupt.”
If those fail, restoring the table from your last database backup might be an option.
