WHAT?! I didn't think this was even POSSIBLE for a non-Source game!!!

Ugh. Anyway. I know the issue all too well, I see it happen to people almost constantly every single time I play a Sourcemod on an open server. The problem is you have a couple files that are corrupt on installation. Why? Don't know. There is a fix. There is a simpler fix created by an Eternal Silence dev.

http://www.eternal-silence.net/forums/index.php/topic,6556.msg85600.html...

Second post down has an executable autofix.