I don't know what your bios looks like, so I can't really help you there. Just reboot your computer, hit the correlating key to access your bios (F2? Delete?), and then do some looking around. If there is an option to turn off your onboard video, it should be somewhat obvious. Just don't go changing a bunch of things without knowing what they do.

Other people have posted that they have similar problems when toggling their active window, but you'll need to go find those threads yourself and see if they found a solution. Unfortunately nobody titles their threads properly, and the same error can be caused by 100 different things.. so it's difficult to reference old threads.