As far as I can tell, the black screen goes away as soon as you change any video setting. Resolution, Color Depth, Refresh rate all remove the 'black screen' (Even if you change them back immediately). However (in my case), when doing this the 3D boxes that were placed are only shown as a grey square, and aren't rendered properly in the editor.
I must note, however, that this is only within the editor. If I run the game even when the editor has the black screen, the 3D boxes will appear correctly.
Note: My video card is an Nvidia 8800 GTX. Latest drivers.