Weird online/offline issues plus DB error
 

We're experiencing some weird issues on one of my forums. Users are being shown as online in some areas and offline in others. I'm not sure if it's everybody or not* but one user at least - Chris - is shown as being online when I view "Who's Online". But in his posts* the online/offline indicator is OFFLINE* and his profile shows that he is OFFLINE and says his last visit was yesterday at 9:20 PM. This isn't true* as he is online right now (10:05 AM) and he has even made posts this morning.

He gets this Database Error when trying to log out: Quote:
Database error in vBulletin 3.8.4:

Invalid SQL:
UPDATE vb_user SET
lastactivity = 1253453069*
lastvisit = 1253454869
WHERE userid = 4;

MySQL Error : Incorrect key file for table './addict_forum/vb_user.MYI'; try to repair it
Error Number : 126
Request Date : Sunday* September 20th 2009 @ 08:54:29 AM
Error Date : Sunday* September 20th 2009 @ 08:54:29 AM
Script : http://www.adminaddict.net/forum/log...321161858a30a6
Referrer : http://www.adminaddict.net/forum/index.php
IP Address : 71.232.***.***
Username : Chris Martin
Classname : vB_Database
MySQL Version : 5.0.81-community-log

For other users* including myself* we can log out just fine and our online/offline status isn't malfunctioning like Chris' is.