2011 - models go into some sort of processing loop

I don't know if the models are trying to auto-refresh/rebuild or what but I'll have an assembly open and at some point the little processing cursor will show up, vanish, show up, vanish, show up vanish.... (repeat infinite loop).  It typically lets me save changes, but not always, but doesn't let me perform most other operations on the assembly.

Any ideas?

gracias

SolidworksAssemblies