When the geodatabase is upgraded to the latest release, as with ArcGIS 10, it’s not always possible for previous releases of ArcGIS to connect to and use those geodatabases.
You can create an earlier version of a file or personal geodatabase in ArcGIS 10 via geoprocessing tools. Specifically via the following “Data Management” tools which have an optional parameter allowing what version of the geodatabase you want to create.
> version 10, 9.3, or 9.2 file geodatabase
> version 10, 9.3, 9.2 or 9.1 release personal geodatabase