Dear Ed,
i had your same problem, in order to analyze better all MRP exeption message i create a
custom report that read
MDKP
MDTB table
T458A
T458B
In this case you can get all message much more fast thats t-code standard MD06.
In this table you can also understand other very important MRP data that could be used for supplementar informations.
Let me Know if i am useful for you.
Daniele