One time I encountered a gradient splotch near the top of my screen. It persisted no matter what application was in the foreground there, so I thought for sure

One time I encountered a gradient splotch near the top of my screen. It persisted no matter what application was in the foreground there, so I thought for sure my monitor had gone bad. Turned off and on, same thing. But then I thought, there's no low to where software construction can go, so even this might be a bug. Rebooted, and presto! No more gradient, monitor was fine. Must have been some Win 7 compositor bug. As I said, there's never a low.