If you have reinstalled the OS as suggested above, then I would consider two other possibilities.
1. conflict between pcmcia slot and accelerator.
2. inadequate power from psu.
Although I do have a PCMCIA wireless network card, it is not plugged in at the moment.
I have an A500 PSU, and an A590 PSU (might be different plug) so I will try those. But how would an inadequate PSU be the cause of write failures? I can see that the 1230xa will certainly draw more power, but wouldn't that be offset by the CF card drawing less than the old HDD?
Both the stability problems and write failures go away when the 1230XA is removed.
I don't see the write failures under WB3.1, those are only with WB3.5. But I do see stability problems under both WB3.1 and WB3.5.