Fix for crossfire starting in windowed in windows 10

You have to change the resolution of the actual system to what you are playing on in crossfire, so if you play on 800x600 in crossfire then you have to change the computers resolution to 800x600.

To change your screen resolution
Open Screen Resolution by clicking the Start button , clicking Control Panel, and then, under Appearance and Personalization, clicking Adjust screen resolution.
Click the drop-down list next to Resolution, move the slider to the resolution you want, and then click Apply.

Note: This is just a temporary fix untill the developers make it possible to play on any resolution no matter what the resolution of your computer is.