I have a Microsoft phone.
After leaving it for a while, the screen goes black and only the time shows (normal / expected behaviour).
If the screen has been black for a little while (about a minute), the phone wont respond to anything.
The time is frozen at the point it stopped responding.
The only thing I seem to be able to do is hold the power button down until the device resets. Then the phone works fine, until the black screen shows again.
What can I do to stop this?