Liza,
What you are trying to accomplish taking the file into Vectorworks. Will someone be using Vectorworks to continue modeling? If so, curves can sometimes be a problem. Delete/turn off such items and try again. They may have to remodel some parts.
If in vectorworks you only need to reference the archicad model you could try exporting a 3D dwg to Vectorworks. It is a much smaller file format.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"