I'm running windows 7 64bits in a vmware virtual machine that was given to me by my employer
After installing Fences on it, I notice this black background color in folder portal, quite annoying since I always put a solid black color for the background desktop
I'm under Mac OS but the instructions below should be very similar for VMWare workstation
shut down windows completely (no hibernate or sleep modes)
open the settings for that VM
you should see a "Display" icon. Click on it.
you will see some setting about DirectX, OpenGL... just enable 3D graphics.
Start your VM and the black background will be gone.
PS: As noted in several post on this forum, you still need Aero enabled in W7.