i get that all the time...it's because you have transperency enabled when you drag a window. It's just telling you that the application you are running doesn't allow the transperency to work. Disable it in your nVidia desktop settings to get rid of the message.
for my settings you just right click on your desktop select 'nVidia desktop manager' from there you will have to look around and see where transperency settings are. Once I get home I will give you a more detailed explanation.