BUG
** This issue is addressed in ArcGIS 9.1 Service Pack 1 (SP1) **
Building network datasets in Network Analyst 9.1 may occasionally produce a file read/write error and abort the build process.
This is a known issue.
Note: This issue is addressed in ArcGIS 9.1 Service Pack 1 (SP1).
Get help from ArcGIS experts
Download the Esri Support App