What version of mysql are you using? Error 127 usually means a record file is corrupted but can also mean table size problems. How big is your active webwork database?
You can try a few things but I would suggest first backing up webwork first, especially the database. mysqldump -u root -p webwork > webwork.sql if you haven't already.
It's probably worth doing '/etc/init.d/mysqld restart' and '/etc/init.d/httpd restart' to reload everything (or whatever your version of these would be) and see if that clears it up.
If not, you may need to repair a table. Probably <course>_set or <course>_set_user. This is fairly drastic and you may want to get some other opinions before going down this path. If you decide to, see
for more detail and tread softly :). You may lose data REPAIR'ing tables.