But in 2011, investigators for the California prison system discovered that the computer determining release priority apparently didn't feel the need to look all that closely. In some cases it couldn't access the full arrest records; in others, the prisoners never had the appropriate conviction information entered into the system at all. And whenever the computer hit a big ol' blank space while reading a prisoner's conviction history, it gave that record a big red "PAROLE PARTY!" stamp and moved right on to the next.

The Fallout:

More than 450 high-risk, violent criminals were plopped out onto the unsuspecting streets, as well as an additional thousand or so deemed likely to traffic in drugs or wreck people's property. So ... time for the cops to get to work rounding these guys back up, right?

Tetra Images/Tetra images/Getty Images
"Can't you just get a posse together? It's taco night."

Nope! That's the best part: Even though the glitch was eventually identified, the California legal system couldn't do a damn thing about those who had already been released. See, this computer system was nothing if not thorough in its glitchiness -- in addition to releasing the unreleasable offenders, it had also placed them on the "non-revocable parole" list, meaning that they never had to check in with a parole officer and could only be reimprisoned if they were caught, say, murdering someone. You know, in addition to however many someones they had already murdered to get thrown into prison in the first place.

It doesn't take a master's degree in criminology to see that this situation was not destined to turn out well. Take Javier Rueda, a documented violent gang banger who had been placed on non-revocable parole: He went down in a blaze of glory when police tried to pull him over for a DUI. One officer was shot but survived; another officer received a fracture (the bullet didn't hit him too hard, we guess?), and Rueda himself arrived at the hospital in much the same manner as a Swiss cheese sandwich (in a baggie).

Sergiy Rudenko/Hemera/Getty Images
So, prison overcrowding still solved, right?

For those Californians keeping count, that means there are about 449 still out there. Sleep tight!

The Tiny Mistake:

When Saint Mary's Mercy Medical Center in Grand Rapids, Michigan, performed a routine upgrade of their patient management software back in 2003, the project went just swimmingly. That is, except for one tiny data field in a certain batch of patient records dropping a single digit during the transition. It's what a patient management software nerd might call a "mapping error" and we might call a "numberfuck."

isak55/iStock/Getty Images
Bigger than a smathfu, yet far from a mathastrophe.

But it's just one little digit, right?

The Fallout:

That one little digit meant that 8,500 unequivocally living people were declared deceased. You think insurance is a pain in the ass now? Try filing a claim when you're dead.

That's what happened to scores of patients who had recently been discharged from the hospital because they were in fact the exact opposite of dead. They started receiving letters from their insurance companies inquiring as to how precisely they were still receiving medical treatment when they were no longer among the living (and the only cure for zombism is an inexpensive bullet to the skull). The errant death notifications were also sent to the Social Security office, which is in turn responsible for determining whether disabled or elderly patients are eligible for Medicare (being a corpse is a big disqualifier).

Jupiterimages/Photos.com/Getty Images
Looking like a corpse is fine; being one is a step too far.

The hospital was quick to point out that it only took them a few days to fix the errors, but as anyone who's ever dealt with a government agency or an insurance company can guess, this was followed by months of having to untangle the mistake. After all, declaring customers dead is something these agencies do on a daily basis. Convincing them that a dead patient is back among the living presumably means that some poor bastard at the hospital had to listen to a shitload of hold music.

If you've ever been called to perform said citizenly chore, you probably noticed that the little card you received in the mail wasn't handwritten with a quill pen and sealed with wax -- no, it was printed out from a computer (quite possibly on an '80s-style hunk of dot matrix, the next best thing to a quill pen). Well, back in 2012, the computer at an Auburn, California, courthouse that was responsible for summoning jurors glitched and went into its "default mode," and apparently, in jury selection software terms, "default mode" translates to "summon every-damn-body in the database."

The Fallout:

Instead of the usual dozen or so, the computer summoned 1,200 people for jury duty -- all at the same bat-time, same bat-channel. Two-thirds of those people gave enough of a crap about doing their duty as upstanding American citizens and asked off of work, cancelled appointments, and freed themselves of those shackles known as friends and family to report to jury duty at the local courthouse ... and instead found themselves trapped in gridlock traffic. The roads weren't prepared for a sudden surge in cars all going to the exact same place, and the would-be jurors couldn't even get to a restroom, let alone the courthouse.

ampak/iStock/Getty Image
She's not a convict. They had to give her a change of clothes.

People late to jury duty were stuck in traffic with other people who were late to jury duty, and everyone was calling the courthouse to say that they'd be late for jury duty. When a small, confused, and frustrated army finally congregated at the Auburn courthouse, people began to suspect that this whole mess was the work of one summons-happy computer, which was later found skulking under its desk, quietly snickering. Court officials apologized "profusely" to the jury/mob and thanked them by informing them that they really would be summoned for jury duty that week -- just not all at once.

With all of those annoyed people in one place, we're kind of surprised a riot didn't break out. The people in this next example weren't so lucky ...

There's just one small but very important detail that keeps this from turning into a huge merchandise giveaway: They have to make sure that the people receiving said credit can, you know, pay it back. Well, apparently no one informed the computer processing the applications of that minor detail -- it started tossing up to $4,000 in credit around all willy-nilly, approving any- and everyone's application regardless of the amount of financial fuckery on their credit report.

So what happens when you take a Kmart in Wisconsin and stuff it full of a crowd of people who see a guaranteed line of store credit as a flashing neon "FREE MONEY" sign?

The Fallout:

A riot. That's what happens: a freaking Kmart riot.

As it turns out, people with less than desirable credit histories apparently have some sort of underground "free money" railroad, and also possibly a "free money" Batphone. Word spread like a Wisconsin wildfire, and before long the store was swarming with people literally fighting to get to the front of the line and get them some totally "free" Kmart goodness.

The store ran out of credit applications. Dealers showed up with reams of them snagged from other Kmarts in the area and started selling them in the parking lot for 20 bucks a pop. And it didn't take long for this crowd to turn ugly: It all started when two young men decided to hulk out and fling a Kmart employee through a glass display case, and it was all downhill from there. That one fight snowballed and transformed the normally peaceful Kmart (Black Friday excepted) into a straight-up bar brawl from an old Western movie, except with fewer cowboys and more Blue Light Special-obsessed housewives. As one eyewitness joyfully reported, "It was a nice brawl. It came from inside to outside. If you go up there, you'll see hair, earrings, all pulled out on the ground."

muratsenel/iStock/Getty Images
Until employees spit-shine them and hang them in Aisle 32.

Police responded in full-on riot gear and dealt every last shopper a good ol' tear gas/Taser combo (we're assuming), and once the smoke cleared, the store's management promptly hung a sign on the door saying that it was no longer processing credit applications. Possibly ever.

But at least Kmart could rest easy knowing that not that much money was at stake. When it comes to financial glitches, s**t can get real in a hurry ...

Luckily, the automated shenanigans only went on for about 45 minutes before Knight discovered and put a stop to them. They were stuck with selling all those overinflated stocks they had unknowingly snatched up back into the market at a much lower value -- but how much damage could be done in 45 measly minutes, really?

The Fallout:

Nearly half a billion dollars, or 10 friggin' million bucks per minute, plus untold numbers of businessmen's boxers ruined by untold amounts of pee.

urfinguss/iStock/Getty Images
To put that in perspective, if you had that much money, you would lose all perspective.

That's how much Knight Capital lost during one 45-minute-long computer glitch. When all was said and done, they'd lost a total of $440 million, more than 1.5 times their revenue for the entire second quarter of the year. Months of work was rendered pointless by a single computer system with the attention span of a 4-year-old standing in an infinite candy store with limitless access to Grandma's coin purse.

Now, you've probably noticed that we've been referring to the Knight Capital Group in the past tense, and there's a good reason for that: Not many companies can survive a nearly half-billion-dollar loss, and Knight was no exception. At the end of 2012, they were acquired by rival trading firm Getco, who hopefully bailed them out with better-behaving computer systems, in addition to the snappier name.

Vstock LLC/VStock/Getty Images
"Getco is a wholly owned subsidiary of Petco. Your investment is safe."

Still, as insane as $10 million per minute and the financial ruin of a major market maker sounds, at least the glitch didn't nearly crash the entire stock market or something ...

But unlike you when you've only got five minutes of your lunch break left and your computer's creeping too damn slowly to load that boxing cat video that your friend just shared on Facebook ("It's a cat! And it's boxing! And you won't let me watch it?! Burn in hell, you electronic torture machine!"), this wasn't a big deal. After all, we're talking about a single goddamn computer in what must be the massive network that makes the stock market tick, and it took Dow Jones literally seconds to switch to a backup computer once the problem was discovered.

The Fallout:

Well, much like how that kitty never stops boxing (never), trading on the stock market doesn't stop just because you can't see it happening. Winning the stock market requires keeping a vigilant eye on what stocks are doing at any given moment throughout the trading day, so for the entire hour that the computer was malfunctioning, scads of investors saw that the Dow was sitting entirely unchanged. Then, once the problem was discovered and the switch to the backup computer was flipped, the average suddenly updated to its correct value -- which, to all those investors who had been unblinkingly glued to that number, looked precisely like the Dow Jones Industrial Average had just damn nigh instantaneously dropped by 200 points. And, in case you don't happen to be a stock trading wiz, 200 points is an A-1 s**t your khakis-level drop.

Spencer Platt/Getty Images News/Getty Images
Traders assumed terrorists must have struck. And, worse, our portfolios were in danger.

This whipped investors into a sellsellsell frenzy that "pretty much collapsed" the New York Stock Exchange and caused the Dow to drop by a total of 546 points -- all within the last couple hours of the day's trading. To put this in terms that a person not wearing a business suit and possessing no less than three mobile devices in belt holsters might understand: There was a stock market crash in 1987. During that crash, the Dow Jones Industrial Average dropped by 508 points. This mess, brought about by a single computer system running slowly for a single hour, caused a larger drop than that.

Luckily, trading closed for the day before the problem could get any worse, and the New York Stock Exchange immediately issued a release saying that they would be upgrading their computer systems. They probably added a third one or something, so we're sure there's virtually zero chance of a repeat occurrence.

Andrew recently tumbled into the world of this particular social media site. You can follow him there, or you could help him out by liking the page for his ska music here!

Related Reading: Let's take our glitches to a creepy new level. Read about the terrifying Manimals of Red Dead Redemption. Hey, gaming history is often made by dumb mistakes. Laura Croft's infamous rack was all the result of an errant mouse click. Rather read about glitches that caused huge disasters? We've got more of those too.

For glitches that would actually be cool, check out If Real Life Had Video Game Glitches and Cheats.