In Easyworship 2009, this black bar problem showed up when I switched to a new laptop with a high-res screen and Windows 10..not sure which is to blame. The slides (both PPT and songs/scripture) show fine on the projector (which is only 1024x768). Black bars show up on the left half of the windows in EWS on the laptop and only a portion of the slide shows though.
The solution is to use that check box mentioned above.... on the EWS icon, right click, select "compatibility" tab, and check "Disable display scaling on high DPI settings". So, it looks like this problem has not been fixed as suggested, but there is a work-around.