Well, the thing is that its a rather clean installation. I didn't even download/install any mods for it since my last HDD reformat a few weeks ago. The only 3rd party stuff I have for it are 2 demos and all the maps I have from my previous installation. I don't think maps and demos actually mess around with the games code?
Also, I have a feeling it has something to do with the OSP mod I have, even though I don't remember even downloading it, much less installing it.