FourSpeed

Minor Update (and possible short-term workaround).
 
I've not had the chance to do much more testing lately, but the past few days, I have not had any Sim PostStart hangs with the problem missions that were regularly locking up.
Rather than clearing folders, as Nealius suggested, what I have done is this:
*  On the first start-up of one of the "problem missions", I start the mission up as a MP mission (before trying it in SP or before trying to edit it).
    (ie. Select Mission --> "Launch as Multiplayer Server", rather than just click "OK") -- so far, the mission(s) have always loaded up without a hang at Sim PostStart.
* At that point, I can either:
   -- Fly it that way as an MP experience
   -- Exit the server, and then restart it as an SP mission the normal way
   -- Exit the server, and edit it (if I'm tweaking things), and it will load / run properly from inside the M.E. with the green arrow button.
 
Why does that work?  I have  NO  idea, but since I've started doing that with any missions involving the Supercarrier, I've had  *zero*  Sim PostStart lock-ups.   Go Figure...
Anyway, I hope that works for other folks as it has for me, and I hope that it might help the devs pinpoint what's causing the lock-ups in the first place, so they can hopefully squash that insidious bug outright...
 
Regards,
4  ~S!~
 
Update / Concession
I'll be the first to concede that this is *not* the ideal solution.   That said, I've experienced *zero* Sim PostStart lock-ups since I started the first (problem) mission start-up of the day / session as an MP server...  A pita, but so far, it seems to work for me, so in the absence of any other solutions, this is the one I've personally found to work for me ... YMMV