Sorry to hear you are having trouble.
i am having the same problem with my screen
This topic has been covered many times in other threads.
Microsoft made changes to Windows that broke DS 8 (black screen) if you have different resolutions for each extra monitor (it will work if the resolutions are identical).
DS 10, does not have this issue and is now only $5:
DS 8 will not be changed as it has not been sold, or supported, for some time now.
Stardock Support Manager