Synapt
What resolution are you trying to run in natively w/ the Samsung? The HP vs15 has a maximum resolution of 1024x768 (the HP vs15 is effectively
not a widescreen monitor).
If you can support it (which is largely dependent on a variety of things), you can attempt to have both screens run separately in different resolutions rather than the native resolution your main samsung is attempting to run in.
HP is a 1028x768 while the Samsung is a 1600x900.
Both can run... on their own.