When importing a DXF file using ModelBuilder the following error appears:"Attempted to read or write protected memory. This is often an indication that other memory is corrupt."
If the original CAD line work was exported to a DXF file, then try saving as a DXF instead.
In one case, there was an issue with the original DWG that was saved to a DXF file.
The release of the CONNECT Edition version of the products (10.00.XX.XX) introduces the ability to use MicroStation DGN files in ModelBuilder.
There may be an issue with the seed/template file that was used to create the original CAD file.
Try copying the linework to a new file that uses a different seed/template file.
Wiki: What's new in SewerGEMS CONNECT Edition
Wiki: What's new with WaterGEMS and WaterCAD CONNECT Edition
Wiki: Importing A CAD (eg. DXF or DGN) Drawing Using ModelBuilder [TN]
Forum: ModelBuilder Importing 2007 .DXF File - Corruption Error