I had this issue in conjunction with the .NET v4 framework update (KB2468871 and KB2533523). The resolution for that issue also resolved the issue I was having with Netflix and Sliverlight. The root cause was that the root certificate store had gone
bad, either expired or corrupted. This most likely occurred during a system restore that had been performed recently.
I applied the rootsupd.exe patch I downloaded at http://download.microsoft.com/download/A/E/4/AE48995A-8C71-4E97-98A1-77752A4F564E/rootsupd.exe. This resolved both failed KB updates and the issue with Netflix.
Details for the .NET installer failures:
Update for Microsoft .NET Framework 4 on Windows XP, Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008, Windows Server 2008 R2 for x64-based Systems (KB2468871)
Installation status: Failed
Error details: Code 800B010B
Update type: Recommended
Install this update to resolve issues in Microsoft .NET Framework 4. For a complete listing of the issues that are included in this update, see the associated Microsoft Knowledge Base article for more information. After you install this item, you may have to
restart your computer.
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Update for Microsoft .NET Framework 4 on Windows XP, Windows Server 2003, Windows Vista, Windows 7, Windows Server 2008, Windows Server 2008 R2 for x64-based Systems (KB2533523)
Installation status: Failed
Error details: Code 800B010B
Update type: Recommended
This update addresses stability, reliability, and performance issues in Microsoft .NET Framework 4. After you install this item, you may have to restart your computer.
Incidentally, as a troubleshooting tip: I determined the cause of this problem by running the .NET installer standalone (outside of Windows Update), which had a link in its error dialog going directly to the actual error in the installer log beyond the 800B010B
reported by Windows Update. It is kind of unfortunate that I had to dig that deeply to get at the installer log. Shouldn't Windows Update be sending that home through WER?