It happens very often when i press alt tab while playing league of legends to change music on youtube or when the game ends. I also managed to take a picture of the screen if it helps. Dont know what category thi is so i put it in systems
http://www.upload.ee/image/4219725/20140820_222739.jpg
http://www.upload.ee/image/4219725/20140820_222739.jpg