If I understood you correctly, this may actually be a normal behaviour. World Racing 2, an older racing game works very similiar to what you describe. Sometimes when I start it, when I have a couple of other programs running in the background, I can see their icons on the taskbar flickering on the bottom of the screen. The game can also freeze completely and won't react to any input untill you ALT-TAB it (the game is running full screen, I see the menu, but the system thinks it's minimalized). Also, that game had a weird screenshot camera, which is controlled by mouse (normally you can't use mouse in this game). What it does, is that it unlocks the mouse pointer, and if you move it too far to the top of the screen and left-click it, you might actually minimalize the whole program. Not sure if the game runs borderless window, but from what you are describing, this might actually do that and this might be a normal behaviour. I've got used to it anyway