There is a button you can hold down when powering up the unit to change the display mode of the MAG. I am not too sure what it defaults to but my TV's don't seem to like the default either. The easiest way to get into it is by unplugging the box, holding down the Menu (botton with 3 lines with 3 dots to the left of those lines) down while plugging the box back in. You should get a menu up that will allow you to change the resolution the box is outputting. Set this to what your TV supports, like 1080P, 720P, or whatever your TV supports. Save and exit and everything should be good.
this is just part of the normal boot-up procedure.. there is nothing needed except to allow procedure to complete... u'll c this every time u boot or re-boot ur mag..