Bugs are common in software, almost every program has one that exasperates its users. But truly unusual bugs that prompt technology to behave as if it was possessed are a rare breed. We round up nine of the most fascinating rare bugs.
2007: Skype down and out
On August 16, fans of the wildly popular Skype internet telephony service noticed that Skype wasn't working properly. It wasn't a brief hiccup, either. For most of its millions of users, Skype stayed out of commission for two days - possibly the longest outage ever for any major web service.
The bug: Throughout the blackout, Skype employees blogged frequently and openly about their attempts to put things right again. But it was only after they managed to restore service that they explained what had happened. Apparently Microsoft's Windows Update had patched the PCs of vast numbers of Skype users all at once, forcing their computers to reboot.
Once all those PCs restarted, they tried to log in to Skype simultaneously. In theory the service shouldn't have been fazed, but the mass connection attempts revealed a debilitating bug in its resource-allocation algorithm.
In a follow-up post, the company said it didn't blame Microsoft. But given that the Windows Update patches that triggered the problem were designed to fix Windows bugs, the saga remains a fascinating example of how exterminating bugs can be as dangerous as leaving them alone.
2007: Pirates, Pirates everywhere
Microsoft's Windows Genuine Advantage copy-protection technology is designed to pester software thieves by denying them software updates, nagging them to pay up, and disabling cool features.
But on August 26, WGA started randomly harrassing folks who had forked over money for their copies of Windows. For 19 hours, it in essence lost its ability to tell a paying customer from a pirate.
The bug: In a post-recovery blog article, Microsoft's Alex Kochis said the company had accidentally sent preproduction code to WGA servers that authenticated copies of Windows as genuine.
The preproduction code assumed the presence of software that provided extra-strong encryption of Windows licence codes, but that software hadn't been rolled out yet. The cocktail of beta code and unreleased software proved poisonous, and WGA began rejecting legitimate Windows licences as fakes.
It wasn't the only time that WGA misbehaved, but it was unquestionably the technology's low point. Possibly as a response, Microsoft has since made WGA less punitive. (It also recently renamed the function Windows Activation Technologies.)
2008: Easier than ctrl, alt and del
When the T-Mobile G1, the first phone based on Google's Android OS, arrived in the autumn, users soon discovered that if you typed 'reboot' on its tiny keyboard, the phone would, indeed, reboot.
It sounds like a benefit, not a bug - except that it happened in every Android application in any context, even if you were simply dashing off an email to your grandma advising her to reboot her PC after installing new software.
The bug: Android, which is based on Linux, shipped with a geeky feature designed to let programmers log in with the highest privileges and issue command-line instructions to the phone from remote devices.
Unfortunately the feature was so buggy that the phone always accepted the commands, regardless of privilege level. And if no remote device was found, it simply executed commands that it noticed being typed on the keyboard at any time.
Beyond the undesired reboots, the flaw opened a security hole of potentially massive proportions; Google admitted as much when it patched Android to eliminate the flaw.
NEXT PAGE: The Day the Zunes stood still