Hi @Anonymous Welcome to Autodesk Community!
This is a known issue and please try the solution from below posts:
AutoCAD 2015 for Mac with OS X Yosemite CRASH!!!
Workaround for AutoCAD & LT 2015 crash frequently on Yosemite with Intel HD 3000
AutoCAD LT 2015 with Yosemite 10.10.1 crashing despite Update 2?
Hope this helps!
Lynn Zhang
Community Manager