Hi,
I had almost the same error (I downloaded the software from http://www.hec.usace.army.mil/software/hec-georas/downloads.aspx, not beta anymore).
Starting format transformation
Transforming to internal format
Validation internal format
Transforming to GDB format
Creating Geodatabase
Unable to cast object of type 'System.__ComObject' to type 'ESRI.ArcGIS.DataSourcesGDB.FileGDBWorkspaceFactoryClass'.
at ESRI.APWR.GISXDE.ArcGISCommun.Workspaces.WSFactory.Create(WSConnectionParams conParams)
at ESRI.APWR.GISXDE.Importer.GDEImporter.Import(XmlReader source, GDEImportFormat format, WSConnectionParams connParams) Failed to import RAS data!
Mikko