Vertical line segments are not supported in an ArcGIS 9.3.1 file geodatabase. Vertical line segments are supported in ArcGIS 10 and later.
Solution
Do nothing. Be aware that the package created is only supported on ArcGIS version 10 and later. Youcannot unpack this package in version 9.3.1.
More information
Packages with data that contains vertical line segments are not supported in ArcGIS 9.3.1 because vertical line segments are not supported in 9.3.1.