Error message when you try to install updates in Windows Vista, and the installation may fail: "WBEM_E_CRITICAL_ERROR (0x8004100A)"

You try to install updates in Windows Vista. However, the installation may fail, and you may receive the following error message: Note This issue may occur when you try to install Windows Vista Service Pack 1 (SP1) in Windows Vista.

This issue occurs for one of the following reasons:

1. The PATH environment variable does not contain the following information:
   %windir%\system32\wbem
2. The Windows Management Instrumentation (WMI) registry subkeys have been modified. For example, if the registry subkey CLSID_WbemDefPath is missing, you receive the error message that is mentioned in the "Symptoms" section.

To resolve this issue, first try Method 1. If Method 1 does not resolve the issue, try Method 2.

Method 1

Add %windir%\system32\wbem to the PATH environment variable. To do this, follow these steps:

1. Click Start, right-click Computer, and then click Properties.
2. In the Computer name, domain, and workgroup settings area, click Change settings.
   
   If you are prompted for an administrator password or for confirmation, type your password, or click Continue.
3. Click the Advanced tab, and then click Environment Variables.
4. In the System variables section, click to select Path, and then click Edit.
5. Add the following at the end of the Variable value text box:
   ;%windir%\system32\wbem
6. Click OK three times.

Note If you are running setup from an existing Cmd.exe window, you must open a new Cmd.exe window after you make these changes. This is because the existing Cmd.exe window will have the previous path value. If you run setup from Windows Explorer, the change is immediate.

Method 2

Run the WMI Diagnosis Utility. To do this, follow these steps:

1. Download the WMI Diagnosis Utility version 2.0 (WMIDiag.exe). To do this, visit the following Microsoft Web site:
   http://www.microsoft.com/downloads/details.aspx?familyid=d7ba3cd6-18d1-4d05-b11e-4c64192ae97d&displaylang=en (http://www.microsoft.com/downloads/details.aspx?familyid=d7ba3cd6-18d1-4d05-b11e-4c64192ae97d&displaylang=en)
2. Double-click the WMIDiag.exe file to extract the files that include the WMIDiag.vbs file.
3. Click Start, and then type cmd in the Start Search box.
4. Right-click cmd in the Programs list, and then click Run as administrator.
   
   If you are prompted for an administrator password or for confirmation, type your password, or click Continue.
5. At the command prompt, type the following commands one at a time and press ENTER after each command.
   
   Drive:
   CD Path
   WMIDiag.vbs
   
   Note Drive and Path are placeholders for the drive and for the path where the WMIDiag.vbs file is extracted.
6. If the WMI Diagnosis Utility reports that WMI is not functioning correctly, follow the steps in the WMI Diagnosis Utility report to resolve the problem.

For more information about Mofcomp.exe, visit the following Microsoft Web site: For more information about errors that you may encounter when you install Windows Vista Service Pack 1, click the following article number to view the article in the Microsoft Knowledge Base: