Just to see the general cause...

What generally brings up the Z80 error on a Neo Geo board?

"Z80 error can be caused by any chip in the sound subsystem or by bad/dirty contacts on the cart slot (some games have sound ROMs in them, others use the sound ROMs on the MVS system board.)"

stolen from this thread:

http://www.neo-geo.com/forums/showthread.php?t=163109&highlight=z80

try a search for z80 mate