I do not know the emulation software but:
- if you have to install windows 8.1, ensure you install the proper directx version and the updated graphic adapter drivers in order to let the application work.
- also, it maybe the emulato does not support full screen antialiasing rendering. To try to fix it, go to the preferences dialog box and in the graphic tab choose "Basic shader" and "0 - (None)" in the multisample dropbox, then restart the program.
It maybe any of that will work
(Author of the program)