I just upgraded my machine with Windows 7 Pro x64, to Windows 8 Pro x64, with the Windows 8 Upgrade Assistant.
Everything went great, but none of the Modern UI Apps open, and they do not show any error messages or warnings, they just close right away I opened them.
I tried to open Skydrive, Windows Store, Photo App,Music App, Bing, Videos , Finances and all the available Modern UI apps on my screen
My screen resolution is 1080p, so it is not a resolution issue, I'm using a Windows account , but i switched to Local account but didn't solved the issue. I ran Windows Update and updated my nVidia video drivers.
I also tried an app called "Metro App Troubleshooter" without luck