Screen Capture Outside Of Windows

Ok, here's the situation: I know how to use WINDOWS BUTTON + PrtScr to capture a screen image. However I would like to print/save an image where this won't work.

I'm trying to run an application I have downloaded (Samsung Allshare), but when I double click it my whole screen goes to a blank Windows screen with a single message box in the middle. This is a "User Account Control" message box. This is what I want to capture. However the "WINDOWS BUTTON + PrtScr" method doesn't seem work here (the only option here is to close this box and return to normal!), and because its an otherwise blank screen, I can't use Snipping Tool or other windows capture features.