In tip 7261 » When you open a security policy related MMC snap-in, you receive 'Snap-in failed to initialize', I explained that this behavior was symptomatic of NOT having the %SystemRoot%\System32\WBEM folder in your PATH environment variable.

This behavior will also occur if your PATH environment variable ends with \.

To resolve the problem

1. Right-click My Computer and press Properties.

2. Select the Advanced tab.

3. Press the Environment Variables button.

4. Double-click PATH in the System variables area.

5. Remove the \ from the end of the string.

6. Press OK and OK.