The problem is that I cannot d/l any updates to the core game, nor can I d/l the expansions, unless I first "register" the original game.  Which I can't do, since the serial number is not valid according to Stardock.  Except, of course, that Stardock are the ones that printed it on the manual.

The issue is with Sins of a Solar Empire, not SOTS - I edited the original post.  The issue remains, I have a legitimate purchased copy of the game, I bought the bundled expansion via Stardocks electronic distribution method and I can't even update the software, let alone play the two expansions.

Think I'm just going to ask for a refund, this is waaaaaay more grief than I am willing to go through to play a several year old game. 

If it is indeed Sins you're trying to register, please contact [email protected] and they'll get it taken care of.