W10M - Lumia 930-why do I get a message every time I try to make an outgoing call?

[Windows Central Question]

W10M - Lumia 930

Got an annoying issue that has popped up today.

Whenever I make an outbound call or receive a message, my screen refuses to turn on. This applies to incoming messages, whenever dialling out or even receiving calls. I can't even unlock/lock the screen .. the phone becomes unresponsive.

Any ideas? Very frustrating.