Forum MYSQL cpu usage skyrocketed this afternoon.. Questions on cause
 

I've been running vBulletin 4.02 PL4 since it's release and on 4.02 for a month or so. Fairly good size forum with over 500,000 posts and 15,000+ users.

Haven't had any real issues until this afternoon. My server loads skyrocketed this afternoon and I notice it was MySQL running at 300% CPU usage. I disabled my forums and the load returned to normal.

Could this be something as simple as a corrupt database table? I'm running a repair on the database now and it has been on the vbulletin.searchcore table for about 1/2 hour now.

If not this, any other ideas?