Thanks for digging in deeper, turns out, one of my earlier drivers was what I needed all along, I just seem to have a crappy USB key that gives the MVSX some trouble.
FILENAME( 19YY, neogeo, 0, 0, 0, 0, 320 )
REGION( 0x200000, CPU1, 0 )
ROM( 0, 19yy-p1.p1, 0x100000, 0x100000, 0x59374c47...