Sounds like a driver/directX/corrupt game issue. Does this happen immediately after the game is closed (within a few seconds)? If so, it's likely an error with the DirectX cleanup. Whenever you exit a game, if it was programmed correctly it would go through a cleanup procedure to clean up DirectX, release memory etc. The function is probably not working properly. This could be because of Drivers, DirectX problems or faulty game files. Reinstall DirectX, Drivers and get latest patches for games. If it persists, contact support for Enemy Territory.