Check the game is using proper video and audio drivers first. If not specify your drivers by altering the game options. If they do match then:

Maybe something went wrong during installation? You can always reinstall RTW, and then try to play the Campaign.

If however you are 100% positively sure nothing went wrong, or after a flawless reinstallment the game still doesn't work properly, you can always try and fiddle a little more with the game settings. Let RTW auto detect the user best performance settings (the gears button in an options screen), and alter these settings afterwards.

If all this fails, try the CA customers support.