Also known as "Crunch" or the "Crunch Monster". It's still not exactly known why a crunch happens, but all the members know it is something to be feared. A "crunch" can make a 400 page thread collapse into 200 pages or crunch a member's total posts! The first noticeable "crunch" happened around 2005 when all the threads in the Fun Board area disappeared.
Sometimes even a whole user account can get "crunched". The first known account crunch happened to the account of Mr Potty, on August 27, 2005. His whole account was suddenly deleted and his posts appeared without a username. It was restored by Captain Serge Stiles, but since then Mr Potty's joining date is completely wrong. First it said "December 1969", then in 2007 it changed to "January 1970". The reasons for the crunch are still today unknown, but it is assumed that it was caused by the 1600 plus private messages (called PMs by most members) in his inbox.
The Crunch is something that cannot be avoided, it is an automatic mechanism built into Probroads. It helps remove un-needed material from the fourm, and also helps reduce overhead, allowing the server the forum is hosted on to run faster.