** This issue is addressed in ArcGIS 9.0 Service Pack 2 (SP2) **
In ArcCatalog, while editing properties of a shapefile, 'raster' is among the selections in the Data Type dropdown list. When clicking OK in the Properties dialog box, an error message occurs:
"Failed to create one of the specified fields"
This is a known issue.
Shapefile and DBF files do not support a field type of 'raster' and it should not be an option in the Data Type dropdown list.
** This issue is addressed in ArcGIS 9.0 Service Pack 2 (SP2).
Click on the link in Related Information below and download Service Pack 2, if necessary. **