I noticed this problem a couple weeks ago when I installed the recent update for windows. All pre installed apps on my start screen had an "X" in the corner of the tile. None of them would open. The only thing that would happen would be I was directed to the desktop and the app would be running in the task bar. By running the app trouble shooter I was able to get the app store working but everything else continues not to work. Settings, maps, weather, mail, etc.