Hi yanyan7
thank you for Posting on Microsoft Answers.
Were you by any chance doing a Upgrade from XP to Vista?
If so, please see the link below.
http://support.microsoft.com/kb/927523The above link should also apply even if you were not doing a XP to Vista upgrade.
Please let us know if this helped to resolve the issue.
Ken
Microsoft Answers Support Engineer
Visit our
Microsoft Answers Feedback Forum and let us know what you think.