I'm affraid I cannot provide much help, maybe some of the A1200 owners & CGFX4 users can provide some insite...
The only thing I can think of off hand is to check and make sure the Z4 board itself is making a good solid connection. Maybe remove it, clean the contacts and put back in place securely? I've heard A1200 owners complain the whole A1200T setup is flimsey..
:-?
