Windows Vista - Code 8000FFFF Windows Update encountered an unknown error

Error when you download updates using Windows Update or Microsoft Update: 8000FFFF

Resolution:
This problem may occur if any of the following values exist in the Windows registry:
HKEY_LOCAL_MACHINE\COMPONENTS\PendingXmlIdentifier
HKEY_LOCAL_MACHINE\COMPONENTS\NextQueueEntryIndex
HKEY_LOCAL_MACHINE\COMPONENTS\AdvancedInstallersNeedResolving
Delete all the three from your registry.
If you don’t know, how to remove it from registry. Please follow the steps mentioned below:
Click Start
In the Start Search box, type regedit.
In the Programs list, click Regedit.exe.
If you are prompted for an administrator password or confirmation, type the password or click Continue.
Find and then click the following registry subkey:
HKEY_LOCAL_MACHINE\COMPONENTS
Right-click COMPONENTS.
Click Export.
In the File Name box, type COMPONENTS.
In the Save in box, click Desktop, and then click Save to save the file to your desktop.
In the details pane, right-click PendingXmlIdentifier, and then click Delete. If this value does not exist, go to the next step.
In the details pane, right-click NextQueueEntryIndex, and then click Delete. If this value does not exist, go to the next step.
In the details pane, right-click AdvancedInstallersNeedResolving, and then click Delete. If this value does not exist, go to the next step.
Restart the computer.