Why do I get a "missing system component" error when installing Windows Vista Service Pack 2 (SP2)?
This problem occurs because system components that are required to install Windows Vista Service Pack 2 (SP2) aren't present on your computer.
One common reason for this problem is that some required system components were removed during a customized installation.
To resolve this problem, we recommend that you use genuine Microsoft software to reinstall Windows Vista with Service Pack 1 (SP1), and then install Windows Vista SP2. For information about installing and reinstalling Windows Vista, see Installing and reinstalling Windows.
If your copy of Windows was included with the purchase of a new computer—the most common way to get Windows—your computer manufacturer provides support for Windows.