Client doesn't show after game.

After a match, the post-game screen, even the LoL window, does not show. There's a tab on the taskbar for it, but the space where the client should be just leaves a ghost image of whatever was occupying that space on the screen previously. I can even drag it around. This has happened for my last two matches, and I have to kill the client through task manager and relaunch to play again.

Please advise.