A bizarre glitch in Apple's software can cause iPhones to shut down when they receive a certain text message. Apple says it's aware of the problem and is working on a fix, but pranksters are sharing information about it on social media and using it to crash others' phones. The problem occurs when the iPhone receives a message with a specific string of characters, including Arabic ones, according to tech blogs such as 9to5Mac. (A Reddit thread also is on the case.) When an iPhone isn't being used, it typically shows a shortened version of the message on the phone's lock screen, and that shortened combination of characters apparently triggers the crash. Affected phones restart automatically. Owners can prevent the problem by using phone settings to turn off message "previews." (More iPhone stories.)