When you are running Windows Vista or Windows Server 2008 on a computer that has more than 8 logical processors, the Windows Experience Index rating is unavailable in the system properties. Additionally, when you run the WinSAT command (Winsat.exe), the command exits with a fatal error message. For example, you receive the following error message when you run a WinSAT CPU -Encryption command:

Error: The WinSAT XML does not adhere to the schema.

This problem occurs on a computer that has more than 8 logical processors. For example, you have a computer that has two quad-core processors and hyper-threading is enabled for these processors. In this example, you have 16 logical processors because hyper-threading makes each core appear as two logical processors to the operating system.

Install Windows Vista on a system with an Intel Menlow processor. The performance score will report an incorrect index number for graphics, thus causing Aero to be enabled by default.

You run the Windows Experience Index (WEI) to measure the capability of the hardware and software configuration on a Windows Vista-based computer. After you do this, the score for 3D business and gaming graphics performance may not accurately represent the actual performance of the gaming graphics. For example, the actual performance of the gaming graphics may be less than you expect, based on the WEI score.

In Windows Vista, the Windows Experience Index rating may display a lower value than expected. You may experience this problem if either of the following conditions is true:

• You start Windows Vista for the first time.
• The Windows Experience Index runs before you update a driver.