I am using MEP 2013 and working on a 3D model that I created using MEP 2010 and have been adding to it over the years and converting the drawing into Navis NWD.I now find that when I want to convert the model to NWC from the CAD model it crashes. I have isolated the problem to the fact that some of the items (chillers, control panels) were modelled and not taken from the CAD standard library because the library did not have the correct configuration. I have even converted these models to multi-view parts but still it crashes.Without having to spend hours remodel the items can anybody tell me how I can get over this problem?  

If you haven't run AUDIT yet you might try that and see if it finds any errors in your original drawing.Dave.

 Yes I tried purge and audit but no change BUT I have got around it by opening the .dwg through Navisworks Simulate and then saving it to .nwd.Thanks for your response.