What sort of things can go wrong with CUPS spool files?

Mac OS X uses CUPS, the Common UNIX Printing System for managing print requests. When you print a file in Mac OS X, you create a CUPS print spool file, which is stored in a cache . The operating system then sends the cached print file to the appropriate printer.

Unfortunately, CUPS files can become corrupt and paralyze print queues. Also, CUPS files can become very large and take up valuable disk space. To avoid these problems, you should regularly clear the CUPS print file cache to maintain the speed and reliability of printing on your Macintosh computer.