[very common; from German ‘glitschig’ slippery, via Yiddish ‘glitshen’, to slide or skid]
1. n. A sudden interruption in electric service, sanity, continuity, or program function. Sometimes recoverable. An interruption in electric service is specifically called a power glitch (also power hit), of grave concern because it usually crashes all the computers. In jargon, though, a hacker who got to the middle of a sentence and then forgot how he or she intended to complete it might say, “Sorry, I just glitched”.
2. vi. To commit a glitch. See gritch.
3. vt. [Stanford] To scroll a display screen, esp. several lines at a time. WAITS terminals used to do this in order to avoid continuous scrolling, which is distracting to the eye.
4. obs. Same as magic cookie, sense 2.
All these uses of glitch derive from the specific technical meaning the term has in the electronic hardware world, where it is now techspeak. A glitch can occur when the inputs of a circuit change, and the outputs change to some random value for some very brief time before they settle down to the correct value. If another circuit inspects the output at just the wrong time, reading the random value, the results can be very wrong and very hard to debug (a glitch is one of many causes of electronic heisenbugs).