In the CD Freaks Living Room, a new sub-forum "Game's Up" was created and most of the fun & games type threads have been moved into this sub-forum, such as "The Acronym Game", "Quest for the Longest Thread on CD Freaks!" and "Big number thread" threads and so on. As some users felt that many of these threads were simply being used as post count boosters, any posts made in this sub-forum no longer count towards one's post count. As you have made around 243 posts (at this time of writing) between the threads moved to this sub-forum, this explains why your post count fell.
See the following post for a better explanation behind this new sub-forum: