Rabbit 6000: conflict between Ethernet and aux I/O

Hello everyone,

 
I'm new on this group, I look if someone already ask this question but I didn't find about Rabbit 6000.
 

 I use aux I/O 16 bit on port A and H and Ethernet connection, but I have many interferences.
 When I disable ethernet, I read/write with no error, but when ethernet is enabled, I sometimes read a 0 instead of correct data, it seems when there is an ethernet polling. 
 

 I see on Rabbit 3000 that the problem could be generated if you do not use shadow registers, but in my case I use all of them.
 

 Did someone had a similar problem?
 

 Thanks in advance
 Emanuele