Game keeps minimizing to taskbar.

[lidec]

I just purchased the Civ 4 complete pack on steam and after installing Beyond the Sword I have encountered an annoying issue stopping me from playing the game. As soon as I start the screen is just black and after a couple of seconds it minimizes to the task bar. If I open it back up it minimizes straight away. Throughout all of this I can also hear audio but it is extremely choppy. I've verified the files twice and Steam says nothing is missing. I also re installed the game and that did nothing. Does anyone have a solution?