Sorry, didn't include the error in the earlier post:
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Executing: GenerateFNodeTNode WaterCourse
Start Time: Wed Apr 27 10:16:27 2011
Populating FROM_NODE and TO_NODE fields...
50434 features processed and 51945 nodes identified.
If your input table was already opened, you may need to close and reopen it to view the updated FromNode/ToNode values.
SetFromToNode,-289 System.Runtime.InteropServices.COMException (0x80041055): Exception from HRESULT: 0x80041055
at ESRI.ArcGIS.Geodatabase.IFeatureCursor.UpdateFeature(IFeature Object)
at ESRI.APWR.ApHydro.GDBHelper.SetFromToNodeDict(IFeatureClass pFC, Int32 debug, ITrackCancel& trackcancel, IGPMessages& messages, String& exMessage, String FromNodeFld, String ToNodeFld, String& sMsg, String sPrecisionFormat) in C:\Projects\10_Final\ArcHydroTools\src\ApHydro\GDBHelper.vb:line 2258, 50434
Failed to execute (GenerateFNodeTNode).
Failed at Wed Apr 27 10:18:01 2011 (Elapsed Time: 1 minutes 34 seconds)