Parts of my Model disappear when adding Material

[Dean Connolly]

This has only just started happening, I created some legs for a chair about 3 days ago and added a Chrome texture. Now when i go to change the material parts of the model disappear?

I'm on Autocad Architecture 2013. 

[Dean Connolly]

OK thats weird, when i sent the model it didn't look like this, but this is how it looks after I assign a new material and it messes up. I'm going to go back and redesign the legs, the file size really shouldn't be that large for such a simple model, something went wrong somewhere. Thanks for taking a look though. 
 
Roy Hirshkowitz said:

What you sent me is a badly mangled AutoCAD 3d solid vaguely resembling chair legs.  Is this what you intended?  Adding a material to the drawing, assigning a material to the object, editing an existing material had no effect on the solid.  No clue how it got that way.  If you need me to debug something that you suspect is related to nXt-- I'll need to see an un-mangled version and a procedure for mangling it.  

nXt doesn't alter geometry, at least not that I'm aware of.  It's much more likely this type of error is due to something else.  It is remotely possible that working in 32 bit caused a low memory situation which caused the model to fail somehow.