[Mediawiki-l] "user_groups" database corruption

[mediawiki at x11.cjb.net]

I've been running mediawiki at sauwiki.com (a site for my school) for a couple of years now.  I upgraded a couple of months ago to the latest version, and it has been working fine until last week, when it greeted me with the database error you can see there now: 

A database error has occurred
Query: SELECT ug_group FROM `user_groups` WHERE ug_user = '1'
Function: User::loadFromDatabase
Error: 1017 Can't find file: 'user_groups.MYI' (errno: 2) (localhost)

Backtrace:

    * GlobalFunctions.php line 451 calls wfbacktrace()
    * Database.php line 408 calls wfdebugdiebacktrace()
    * Database.php line 358 calls databasemysql::reportqueryerror()
    * Database.php line 734 calls databasemysql::query()
    * User.php line 692 calls databasemysql::select()
    * User.php line 622 calls user::loadfromdatabase()
    * Setup.php line 209 calls user::loadfromsession()
    * index.php line 63 calls require_once()

I tried to run check tables on it, but it didn't seem to have any effect.

I found this person:
http://mail.wikipedia.org/pipermail/mediawiki-l/2005-September/007350.html
who had the same problem, and the suggestion was to ask the host about fixing the database, but when I contacted iPowerweb they told me their databases were working fine, and that they didn't support third party software.

When I use phpmyadmin I get a similar error when trying to browse the "users_groups" table, but the other tables are still there.

So what I am asking, is how can I restore my wiki without losing the data?

Thank you,

Brian