Hi,
This dialog pops when I switch from 2D to 3D view. This happens after I placed an object (20 stories building) into my master file. The problem's gone when I remove this object from Library manager.
Does the error actually prevent the model from generating? Does it just affect the part itself or the whole model?
The only fix I can think of is to try resaving the building as a new library part. If it still has the problem try just saving floors 1-11 (or 0-10), and keep testing by halves until you find the offending bit in the source model. It's a bit tedious but the binary search zeros in on problems in the fewest steps (except for the occasional inspired guess).