The only possible thing, though I don't see how this would make a difference, is that I had installed a new secondary hard drive on my PC and moved my GOG folder and conversely, my NWN Diamond folder, to the new drive. I then attempted to install the PRC. Could it be some kind of registry issue with it having a conflict after moving the folder?

I attempted to install the PRC, opting to use the RAR version and extracting all the files to their appropriate folders. When I start the game, though, none of the classes or races or anything from the mod show up. Any ideas?