This might be a good time to ask for a copy of your gameex.ini, log.txt, and theme.ini files to avoid further confusion regarding the background images. As for displaying the images correctly, I think you may need to qualify that with a little more information. GameEx does a pretty good job trying to keep the videos proportionate, however, no frontend is going to switch the displays back and forth to perfectly crop from horizontal to vertical. The only way possible would be to, perhaps, have two MAME setups going for example, one with all vertical games (and the foreground masking for that setup to crop as closely as desired) and the same for horizontal.