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It sounds like a bug with the software. If you do not have the original SBS 2003 machine, I think you are out of luck. You can also try restoring from backup after staging a new 2003 server in a separate domain, but I am not sure if that would work either.
It has been hit / miss with 3rd party software that reads the EDB file offline. I think you should try Microsoft Exmerge utility to convert all exchange data into outlook file format. Download from here: http://www.microsoft.com/en-us/download/details.aspx?id=2743
See if the following article would help:
https://social.technet.microsoft.com/Forums/en-US/82b432a2-12e7-46f7-b27d-46a1a94c23f7/how-to-get-outlook-recovery?forum=officeitpro