In amongst the otherwise fun stampede that befell Apple and AT&T's servers yesterday, some less humorous problems were also taking place. Numerous tipsters reported to Gizmodo during the day that they were being logged into other people's AT&T accounts while going in to try and sign up for an iPhone 4 upgrade. An insider source suggests that this was caused by a major fraud prevention overhaul of AT&T's software last weekend, which was followed by "absolutely no testing" prior to the iPhone 4's launch. Tsk tsk. The network itself has responded by saying it's unable to replicate the issue and is looking into it. While it's doing that, a bunch of people might be "looking into" your AT&T account details. Sleep tight now.