mvme162p-334 exception: parity error external message

My mvme162p-344 is generating "exception: parity error (external)".  Any
ideas??  I checked the debug documentation and could only find "parity
error" but not "parity error external".

This error occurs randomly after my program has been running from anytime
between 1 and 20 minutes.

I ran all memory diagnostics via 162DIAG and they all passed.

Thanks in advance.

Duane