Hi Standal.
Some things to verify:
1. Do you have the latest vSphere patches installed? (We have fixed a few graphic corruption bugs in the last ones)
2. Could you try this registry setting: View Accelerated – 3D Graphics with Horizon View 5.2
If you still see issue please go ahead and open a Support Request, when you do that then please reference "Bugzilla 936724"
(This is an internal Bugzilla number that will help our support to assign it to the right place)
// Linjo