In addition to reports of faulty disc drives in the Xbox One, some users are claiming a problem in which the system will not boot past the initial green logo screen.
Multiple users have posted threads on Microsoft's Xbox One support forums, referring to the issue as the "Green Screen of Death," an obvious play off of the Xbox 360's Red Ring of Death. Some responders that suffered from a similar issue claim that turning off and on and power cycling the system will eventually get past the problem, but Microsoft has yet to official post a response.
Again, there's no reason to start a massive panic here as there have only been a few reported cases, none of which have officially been acknowledged by Microsoft. It's not unusual to experience some defective units during the launch of new hardware, but like Sony, claims like these can be quickly blown out of proportion.
When the PS4 launched, user reports of faulty consoles was rampant on the internet, yet Sony claims less than 1% of the total units shipped were actually affected. The internet sort of has a way of making things seem like a more widespread problem then they actually are.