Have you installed the newest video drivers for your model? If not download them from the manufacturers website.
Since Windows 8 has not been released yet not all drivers are going to work with it. Some drivers are very specific about the operating system version, so you might have to wait until they
release Windows 8 drivers (if they make them for your model).
If the drivers don't install, try installing them in compatibility mode.
Troubleshoot Compatibility
This can help with some (but not all) programs/drivers:
1) Uninstall the program if it's already installed. Then when you install/reinstall it instead of double clicking on the install file right click it and select "Troubleshoot Compatibility"
2) Then click "Try Recommended Settings" and in the next windows click "Start the Program" to install it.
3) After it installs see if it works correctly. Please note - some programs may not be able to run in Windows 8.
