After a period of time editing, I notice the the play buttom in the program window is a square instead of a triangle. When I click it to won't play my cut. I also can't play by hitting the spacebar while in the timeline. My only solution is to quit the program AND restart my PC running Windows 10 Pro. I am also running the latest version of PP. When I open it again everything is fine for maybe an hour before it does the same thing.