I just upgraded from 7 to 8.1, and I am having a rather serious issue. I have two graphics adapters, an nvidio 8600 gs and the onboard intel hd4000.
Now, in 7, I could use both at the same time to power four monitors. In 8.1 however, when I attempt to plug in a monitor on the onboard video the entire windows 8.1 GUI crashes and goes black - and then continues to reset indefinitely. The mouse shows up, then resets back to the center of the main screen. I can move the mouse to the monitors on the onboard graphics and the add-on graphics card. Windows won't reload the GUi. If i unplug it, it goes back to normal but my user is no longer logged in and my session is lost. I don't really even know how to research a solution, my google fu is weak on this issue.
I am using 8.1 enterprise if that makes a difference. Maybe enterprise doesnt support it? Don't see why not though.