In general a black screen simply indicates and incomplete or incorrect download. While downloading, did an error show?
A black screen can be caused by:
1) An incomplete download (but you say you've run the download multiple times, have you tried opening VaM_Updater -> Options -> Sync / Repair All? Were there any issues or error messages during download?)
2) Non-English file path or very very long file path. Have you tried moving the folder to the root of some drive, like D:\VaM?
3) Video card without a proper update, have you updated your video card drivers?
4) If you press the letter "M" on your keyboard, while Virt-a-Mate is open, it toggles the screen going black. Does pressing "M" (once it's loaded) or F1 show anything.