** Using WeBWorK **

Thanks so much Danny,
Your link did the trick.
For the record, here's exactly what I did.

cd /var/lib/mysql/
Inside here, the webwork/ directory was not readable to me. Hence:
sudo chmod 775 webwork/
cd webwork/
sudo myisamchk -r -q MAT258-Bradley_key.MYI

Also, this link has instructions for backing up the database:
http://www.roseindia.net/mysql/mysql_backup_restore.shtml
I followed the directions before doing the above, but I got
an error because of the corrupted table I was hoping to fix.
So in the end I just fixed the problem as above without backing anything up. Luckily it all works fine now.

Thanks again,
Andy