When switching between Mixer Window and Project Window, i use the F3 button on my keyboard.
When switching from Project Window to Mixer Window, the Mixer window shows a white screen for a split second before showing the user interface.
1.) Open Empty Project.
2.) F3 to open Mixer.
3.) Repeat step 2.
System:
Windows 7 64bit - i7 920 - 12GB RAM
Cubase 8.0.5
NVIDIA GeForce 8400 GS - driver v9.118.13.4144