If I remember right, the Supra ROM version can mess things up no end (if it isn't the latest). I can remember problems way back when with the A500 sidecar from Supra.
Since then I have used Asimware CDFS and it has always worked, on everything from my A1200, to A2000 or A4000.
There are times when I'll swear it depends on the phase of the moon though....
