[Zope] import/export errors

[nwingfield at dixon-hughes.com]

Having exported a ZEXP file from one Zope instance (Zope 2.7.2, Python
2.3.3), I get the following error when trying to import the ZEXP into
another Zope instance (Zope 2.6.2, Python 2.1.3).  I've never before seen
this error, and I'm wondering if anyone can help.

Traceback (innermost last):
  Module ZPublisher.Publish, line 98, in publish
  Module ZPublisher.mapply, line 88, in mapply
  Module ZPublisher.Publish, line 39, in call_object
  Module OFS.ObjectManager, line 530, in manage_importObject
  Module OFS.ObjectManager, line 546, in _importObjectFromFile
  Module ZODB.ExportImport, line 79, in importFile
  Module ZODB.Transaction, line 235, in commit
  Module ZODB.Transaction, line 350, in _commit_objects
  Module ZODB.Connection, line 305, in commit
  Module ZODB.ExportImport, line 148, in _importDuringCommit
SystemError: Failed to import class struct_time from module time

ID:[{20040830095057.711.8301683122-12.6.18.86}]