Game won't start, Can't get discount for rebellion

As the title states, I can't launch the game properly through steam. It has me login and register my CDKey every single time, but now it's begun to simply freeze at that part, Only letting me select quit instead of register.

As well, when I try to buy Rebellion and apply the game discount, it doesn't recognize that I have the game linked to my account, which I have done several times now, and when I choose the option to enter my CD Key to get the discount, I get nothing but a 500 - Internal Server Error.

This is an excellent game and I would like to buy Rebellion, but I'm very close to playing it another way, and if this keeps up, I'll never trust Stardock with my money again.