INETORGPERSONFIX versus INETORGPERSONPREVENT
When trying to upgrade a Windows 2000 domain with an Exchange 2000 box, apparently some very strange things can happen to the Schema. Microsoft KB 325379 talks about this. If you try to run adprep before using an ldfide fix on the schema, several values get muddled.
http://www.mattschroeder.com/home/
Here