I get the same error in a certain scenario, when using RDC:
(1) I login to my local workstation at work, where I'm running DesktopCoral (workstation has two monitors)
(2) I go home, and use Remote Desktop Connection to connect to my workstation at work, via my laptop (laptop has one monitor)
(3) I get the error (additional popup every second or so), until I restart the app