@hacha-dorada:
Try lowering your memory split. I had same issues as you. After lowering gpu_mem from 384 to 256 (or even 128) (on a Raspberry with 512 MB RAM) now almost every neogeo game runs with pifba (source installed).
Please take a look at http://www.raspberrypi.org/forums/viewtopic.php?f=78&t=50587 for more help.
