ML1200 faulting on Expansion Module

Hi,

I have a ML1200 that is faulting very occassionally, with an error that says something about not being able to read from the expansion module (I cannot remember the exact wording & forgot to take a screen shot.)

There is a Net-ENI that is connected to this, but is useless under this condition, I have to connect via Serial.
I have a couple of questions:
1. Does a fault like this render 1x of the comm ports un-operational, or at lease prevent access via the Net-ENI?
2. What could this fault be, and can it be disabled?

I cannot recall the exact time frame between events, as this PLC has not been used up until now, so will try & track it.

Latest error attached, is this avoidable or requires a hardware replacement?

I had a Micrologix 1100 that had the same error that would occasionally appear. The only expansion I/O it had was an IF4 card, I checked wiring, replaced the expansion card, and still the fault would randomly appear.

I replaced the processor and the problem went away. I used the processor on a later project (didn't want to throw it away) and the problem would randomly occur again.

So, long story short, the processor was the fault source, and replacing it was the only way I found to fix it.