Situation At Hand:
- You receive an invalid confirmation to activate your copy of Windows.
Error message :
“Windows will expire in X days / hours”.
Possible Root Cause :
- This is due to a beta / pre-release of Windows Vista SP1 which was installed on your computer previously.
- End users are not encouraged to install pre-releases unless of course you are technically equipped 
To resolve the issue at hand :
- The pre-release of SP1 has to be removed from your computer.
Steps:
- Go to program and features and attempt to locate Service Pack for Windows to uninstall.
- Search for “Service Pack for Microsoft Windows (KB936330)”.
- If the beta version is not visible you might need to perform an in-place upgrade or custom installation to resolve the issue.
- After uninstalling KB 936330 you will need to reinstall Windows Vista SP1 manually to overwrite the faulty settings.
Windows Vista Service Pack 1 All Language Standalone (KB936330)
Hope this helps
