You should try updating the video game first. The video game might be conflicting with your computer's settings, so I recommend that you update the video game before you try another solution. Follow this link and select the update that applies to the current version of the video game:
http://www.atari.com/rollercoastertycoon/us/downloads
Remember to select the correct update for the video game.
If the update does not solve your problem, try updating Windows by using Windows Update. Then, try to update DirectX. Please state your current operating system in your next post.