I get the same error. Are you using vista? That's the OS that I am using. This is the same error that I get with his other program. I wonder if it is a vista thing.
Do you have a DVI connector on your video card? If so you can do what I do, buy a dvi to hdmi converter and spanning will work. That's what I did to get it to work. Because my tv only has HDMI connector.
This is in response to kingb33