Hi Mike.
When the image changes when using a converter, you may need to re-select the screen resolution on your computer/laptop.
Please have a look at article 10418 on www.PrometheanKB.com, depending on the board size, you will need to make sure you have the correct aspect ratio set.
You can right click on desktop and click on screen resolution.
I hope this helps, I've created a separate support case to assist you with your issue. Your case reference is 00424790.
Adam
Promethean Technical Support