ATI Radeon
When you try to play Zoo Tycoon 2, you may experience the following issues with any one of the ATI Radeon graphics adaptors:
• When you play Zoo Tycoon 2, after you change AGP or PCI settings in the ATI Catalyst Control Center, Zoo Tycoon 2 may not appear correctly. To resolve this issue, follow these steps:
1. Quit all the programs that are running.
2. Click Start, and then click Shut Down.
3. In the Shut Down Windows dialog box, click Restart, and then click OK.
4. After your computer restarts, perform steps 2 and 3 one more time.
5. Start Zoo Tycoon 2.
• When you play Zoo Tycoon 2 after you perform a clean installation of the operating system or update the driver for your ATI Radeon graphics adaptor, Zoo Tycoon 2 may not work correctly. To resolve this issue, follow these steps:
1. Quit all the programs that are running.
2. Click Start, and then click Shut Down.
3. In the Shut Down Windows dialog box, click Restart, and then click OK.
4. After your computer restarts, start Zoo Tycoon 2.
that is from the offical microsoft page if you have tried all that and the game still does not work then you need to contact microsoft/blue fang irect as we cannot help you further sorry.
http://zootycoon.com/support/techsupport.htm