Well, the Apollos weren't known for stability. You may still be dealing with a heat or power problem, though.
What power supply are you running? If it's the C= stock A1200 one, that may be your problem. The system might not be getting quite enough juice... I had to update my A1200 power supply for an old GVP 030+ board.
Also, how did you try cooling the 030/882? Just a fan probably won't do much good by itself. A small heatsink attached with a good thermal compound would probably help keep the core temperatures quite a bit lower than just aiming a fan at the chips. I know it sounds corny, but the little chunk of metal and the heatsink compound really make a HUGE difference.
