Hi, it's the one i made in this thread
http://forum.attractmode.org/index.php?topic=1300.0 ?
It's kinda weird the issue you talk about.

I usually test them in windows 10 and on my raspberry pi. I'm not sure if you are talking about the background (wallpaper) or the art (the tv, console, etc) but i will try to help. Try this:
-Redownload the file in case it was somehow corrupted
-make sure the files bkg.png, bkg2.png, robo.png and robo2.png are on the main folder of the layout
-in attract mode, go to options/displays/ and select the display in which you are using the layout. Make sure you have selected robospin-megadrive as the layout of the display.
-then go to 'layout options' and search the following options...
-in 'select bg image or panscan'... it should have 'blue' or 'retro' selected. change it if not.
-in 'select cab skin' it should have 'megadrive' or 'genesis' selected. change it if not.
-If it still doesn't work post here the layout.nut code and it'll look it, but it's kinda weird.