Looks like the error only occurs on Bit 0. So this means that probably the D0 or D8 line not quite stable or protected (you could try and trace the circuit and see if there's something visibly wrong with the signal line). Did you try different zorro slots? If this helps, cleaning the contact may do good to the 'faulty' one.
However, the PIOWriteMem Timeout indicates that there's a problem with the bus timing.
I'm sure Jens Schönfeld will be glad to help fix this.
