Database Multiple Keys Error

Greetings everyone,

I have this site WordPress 3.2.1 with Buddypress and Multisite enabled. I am getting some performance issue and when I read the log file I am getting this:

[snip]

Actually this is the only one left in all problems I got.

I uninstalled the bbforum to see if that caused the error but it still active.

So now, I would like to ask about this error what causes this and how to fix this?

The problem is that it creates error.log to explode up to 100 mbs so I have to delete it everyday…

Any help is gladly apprecitated

~ Unwired