OK, seriously computer ignorant old woman here.  I bought Galatic Civitions II Gold Edition, which includes Dark Avatar, from Amazon.  I installed it and played it, worked fine.  Then I came here, registered it and updated it--now when I try to start the game, it tells me to run setup.exe on the disc or reinstall from Stardock--can't find setup.exe don't understand why I should reinstall from Stardock.