I have the same problem with my MIMO 720F Touchscreen USB Monitor (7" 800x480) built in the case. I use latest driver 7.5 M0 and AIDA64 for monitoring.
Windows 7 = no problem
Windows 8 = no problem
Windows 8.1 / display in landscape = no problem
Windows 8.1 / display in portrait = sucks / black display, i see only mouse cursor
