Mark,
You don't say whether your 'friend' is on mac or pc, not that it necessarily matters in this case.
I found any time I brought in custom attributes, specifically materials and fills, from 10 to 11 ac would crash.
HTH
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"