Failure to load save

[GarrisonChisholm]

Good afternoon folks-  I am not looking for a magic answer, but am wondering if anyone else has experienced this.  I am (well, was) in year 23 and playing at a steady serene pace.  Suddenly however when I went back to load the game it will start to load bits of the first screen (the KAC window, and sometimes the KCT window), but then freeze and never load anymore- the KSC never appears, the screen stays blank.

I went to a back-up save and renamed it as Persistent to try to get it to load, however the same thing happened.  I have since started a new game.

I have 2 theories about what might have caused it to hang up- first, that I was "rolling out" a rather (but not extremely) complicated rocket, and that the game didn't like the fact that it was saved during the roll-out.  Secondly, I wonder if it has something to do with having landed new Kerbalism parts on Duna.  I strongly favor the first theory, but am wondering if anyone else has had experiences that could shed light on this?