Occasionally, I log in to wordpress admin and get the message "You do not have sufficient privileges to access this site" or something similar. It's always because the usermeta table has lost all its rows. When I run "repair table usermeta", the rows are restored and everything is fine. This happens at least once a week though, so I'm wondering what could cause the usermeta table to frequently drop all its rows? There are about 12,000 or so rows representing around 500 users. Maybe that's too many users for a single wordpress blog?
Thanks in advance!