Figured it out. Our custom  field is a drop down list  that can point
to any site  for the source , select a view, and even link them together
and do cascading filtering. Anyway, once the list was restored on the
new farm, it could not get to the url that was the source for the drop
dodown list which was pointing to the old farm  and it was throwing a
null object reference.

Just wanted to post the solution incase someone else runs into
something similiar. The farm appears to be the barrier.