neutrinoccThere is actually a registry setting for VNC, but for some reason it keeps getting reset.
They key is:
HKLM\Software\RealVNC\WinVNC4 Create a key called BlankScreen (REG_SZ) and set the value to 1
It also gets set if you go into Status on the VNC tray icon and blank the desktop in advanced settings.
If anyone figures out how to keep it set, please update it