Don't do that, do this:
site:www.mysite.com/forums/

By doing that you can have it searching just for the script ubbthreads.php which can bork things in the engine.

Also, it won't index your posts invidicually, it'll do threads, so you should have so many threads shown.

Also, what's your domain name so we can look at it and try to figure something out?

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
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