I recently had to rebuild my Wii's SD card and set up everything again. For some reason the Mame 2003 core will not accept diagonal inputs anymore. Every other core is accepting them, so I know it isn't an input issue; and it is a fresh install, so other than the .cfgs for the arcade resolutions, everything is stock. Any ideas? (edit) The default analog deadzone for MAME 03 is set to .20, and Retroarch's is set to .50. This prevents diagonal movement. Easy fix: set RA's deadzone to whatever you prefer and set MAME 03's deadzone in the quick menu to 0. This might be helpful to somebody setting up the core on a fresh install, so I'll leave this here.