Prefix:  Solidworks 2015 sp4

          - I have an assembly with parts built using mastering modeling techniques. (Each part references same master model part)

Problem:  Upon rebuilding assembly, specific features (usually just a few surface trims) in a few parts will blow up(red).  "Some times" I can close the whole assembly, reopen and all features will be fine.

These features (specifically surface trims) have no external refs.  I can go in and manually repair these features (I have to re-select the cutting surface and the surfaced I want trimmed.) and then I can continue on my merry way, but next time I open the whole assembly, they crash again.  This seems to be an intermittent problem with no clear root cause, besides rebuilding the main assembly.  This has been an irritating little problem throughout this project.  Hopefully someone can give some input.

FYI.  I cannot share data due to NDA.