Computer Gremlins, the unseen menace

Few people know it, but Silicon Valley was once a major home for gremlins. As the computer people set up shop and ruined the magic gremlin forest, gremlins decided to make life a little more annoying for computer users everywhere. These gremlins are specially developed strains, different in many ways from the ones that bothered the RAF during World War II. Scientists have discovered the following distinct sorts of computer gremlin:

Logic Saboteurs

(Graemlin irritatis algorithmii)
This gremlin subspecies is the archnemesis of coders and hackers everywhere, probably because their home was ruined by caffeine-slurping coding geeks. They lurk within the computers of hackers, and are the prime reason why hackers praise the Gods of Debugging. Whenever the hacker is not 100% focused on the task, the logic saboteur will introduce bugs into the code and enjoy the look on the baffled hacker's face. They have the special ability to turn their bugs invisible, but only to the hacker who was hacking while the gremlin worked its mischief.

Hardware Tinkerers

(Graemlin irritatis electromechanicus)
Possibly the least specialized of the computer gremlins, these delight in figuring out how hardware components work, often failing to put them back together in functional order. They will take apart your slot-in DVD-ROM while you're not home, and mess up the loading mechanism in the process. They especially like fooling around with overclocked processors and water-cooling rigs. Their preferred habitat is i386 PCs, the cases of Macintoshes are too small for them, and big UNIX servers and mainframes are too hot.

Phantoms of the Operating System

(Graemlin irritatis systematicus)
These gremlins make life annoying for every computer user, from home computer dabblers to coders. They have adapted to a completely non-physical form, and they in fact live as processes in the operating system (they can mask themselves so top won't pick up their presence) where they are aware of the user's actions, and do everything they can to throw their flies into his ointment. Inexplicable kernel panics, programs dying for no apparent reason, bizarre memory leaks, Emacs, all the work of these gremlins. They feed on computrons, so they make your system slower to get you to buy faster hardware to keep them well-fed.

Networking Demons

(Graemlin irritatis teeceepipensis)
Primarily residing at ISPs and in other large networking hubs, these live inside routers and servers. They speak TCP/IP fluently, and take delight in randomly rearranging the flow of packets to make the network do strange things. They take servers down when they need to sleep, and are the cause of many a happy 404. The BIND DNS server software is a favoured home of these.

Several other computer gremlins exist, but these are by far the most abundant.