It happened to me and it coincided with the screen going black when I made phone calls. I think it's some sort of sensor issue. I sent my phone in for repair on 1/31/13 and I am yet to get it back. I am really keeping my fingers crossed that they don't return it with the same issue or possibly worst. I have read horror stories on this forum about Nokia repair. Good luck.
The screen goes black on me too when i make phone calls! I've read that the fix is to blow the top part of the phone with your mouth or an air duster. Sometimes it works and sometimes it doesn't.... Such a bummer... i'm probably gonna have to send in my phone to be repaired... sucks dude
happened to me.
the phone senses the proximity sensor is blocked, like it would be if the phone is in your pocket. try blowing air at the top edge by the FFC.
if there's a screen protector, cut off the bit above the N of nokia logo.