I worked at a timesharing shop many years ago. One machine ran an operating system called Micos. When something went wrong, an error number would be printed on the console. At the end of the manual for this system was an appendix that described the error numbers in more detail. My favorite (which was printed when the disk drive crapped out) was: Error 4: this is definitely a hardware or software error.
(From the "Rest" of RHF)