Installing vCenter Server 4.1 on Windows 2008 R2 fails with the error: Error 1402. Could not open key: UNKNOWN...

Symptoms :
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• Cannot install vCenter Server 4.1 on Windows 2008 R2
• Installing vCenter Server 4.1 on Windows 2008 R2 fails
• You see the error:
• Error 1402. Could not open key: UNKNOWN..

Note: This issue may also occur with other VMware products, such as VMware Workstation.

Resolution :
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• This issue occurs due to insufficient or incorrect permissions on a certain registry key or its parent container.

Steps:
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To resolve this issue, apply appropriate permission to the Windows Registry.

• Click Start > Run, type regedit, and click OK. The Registry Editor window opens.
• Navigate to the parent container KEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Components. 
• Note: The S-1-5-18 key may be different on your computer.
• Locate the correct container registry entry, right click the parent container registry key, such as C9AE13788D0B61F80AF18C3B9B1A1EE8, and click Permissions. Note, the relevant container registry entry causing the install issue can be identified in a fully detailed error message appended to the error outlined in the above Symptoms.
• In the Permissions dialog, click Add and add the Administrator, Administrators and SYSTEM accounts.
• Click each account in the list and ensure that it has Full Control = Allow and Read = Allow permissions.
• Select the Replace all child object permissions with inheritable permissions from this object check box and click Apply.
• In the Owner tab, click Administrators in the list, select the Replace owner on subcontainers and objects check box and click Apply.
• Retry the vCenter Server 4.1 installation.