Video artifacts appear in Windows virtual machine when using a projector or a second monitor

Symptoms

Video artifacts appear in Windows virtual machine after connecting projector or second monitor. After you remove the projector or monitor Windows screen flashing into many pixels.

Cause

This problem is connected with WDDM 1.1 Intel drivers behavior, which has been implemented in Parallels Desktop 7 for Mac.

Resolution

In order to eliminate this problem please do the following:

1. Shut down the virtual machine;
2. Go to Virtual Machine menu (or Alt+click on the Parallels icon in Coherence) --> Configure --> Hardware --> Boot Order; 
3. Insert the following boot flag:

video.wddm_1_1=0

        4. Close Configuration window and start the virtual machine.