Today some of my windows 8 apps started acting strangely (in windows 8.1). When I click on certain of the tiles, the app starts to open and then reverts to the start screen. Apparently the app is still partly open, because when I move the mouse to the upper left corner, the thumbnail of it appears. If I click on it, I get the opening screen (the colored one with just the logo), and then it clicks back to the start screen, and the app never completely opens. I first noticed this with Microsoft Solitaire collection, so I uninstalled it and reinstalled it, and now it works fine. However, the same behavior is exhibited by several of the other apps, such as Travel, Finance, and New York Times. Reading List also acted like this for a short time and now is working ok. Rebooting the computer didn't help. Any idea what's going on?