Since installing PP Classifieds, we've experienced some users post counts going crazy, for example in to the billions of posts. This is a bug that affects more than just our installation, I'm in the process of doing some research to help Chuck and the team. I have already found this report of the same problem with a user using PP Classifieds
Post count going into Billions for some users! - vBulletin Community Forum and I'm investigating 2 other claims.