No Dennis, to my mind I have not done changes at all. I do have two monitors and your post brought back vague memories of avid xpress only displaying working video on the primary monitor. I dragged the program onto the other monitor but no change.
Made a new project today, imported some clips and the problem is still there – still frame on playback, regular audio and “normal” playback when I scrub backwards and forwards.
Anyway, the weekend is here “down under” so I will put the brain in freewheelin mode and see whether the light bulb goes on.