A previous schema extension has defined the attribute value as "%1" for object "%2" differently than the schema extension ...

A previous schema extension has defined the attribute value as "%1" for object "%2" differently than the schema extension needed for Windows Server 2008 R2.
[Status/Consequence]
Adprep cannot extend your existing schema
[User Action]
Contact the vendor of the application that previously extended the schema to resolve the inconsistency. Then run adprep again.