iMac potential graphics issue
I have noticed my iMac screen locks on the attached distorted screen. It seems to happen when the mac is left unused, before the screensaver should kick in. This is an intermittent fault. The screen will stay on like this indefinitely (so the screensaver and sleep mode is not kicking in) but the screen returns to normal if I press escape.
Has anyone experienced similar or recognise what the issue may be?
iMac 27", macOS 10.14