Windows 7: Updates KB2478662 & KB2446710 fail with error code 80070BC9

Systeem is Windows 7 HP SP1 64-bit.
Since 25-1 updates KB2478662 and KB2446710 (security supdates for .NET Framework 3.5.1 on Windows 7 Service Pack 1) fail with error code 80070BC9.
All other updates including .Net 4 install normally.

I have tried:

• clean boot
• updates one by one
• fixit
• system update readiness tool (kb947821)
• sfc scannow

I would like to de-install .Net 3.5.1 but this feature does not seem available in this Home Premium system.

Please advise (other than system reinstall)

See if this helps ....

download TFC by Old Timer TFC - Temp File Cleaner by OldTimer - Geeks to Go Forums and save it to your desktop.
Save any unsaved work. TFC will close ALL open programs including your browser!
Double-click on TFC.exe to run it. If you are using Vista/Windows 7 right-click on the file and choose Run As Administrator.
Click the Start button to begin the cleaning process and let it run uninterrupted to completion.
Important! If TFC prompts you to reboot, please do so immediately. If not prompted, manually reboot the machine anyway to ensure a complete clean.

TFC (Temp File Cleaner) will clear out all temp folders for all user accounts (temp, IE temp, java, FF, Opera, Chrome, Safari), including Administrator, All Users, LocalService, NetworkService, and any other accounts in the user folder. It also cleans out the %systemroot%\temp folder and checks for .tmp files in the %systemdrive% root folder, %systemroot%, and the system32 folder (both 32bit and 64bit on 64bit OSs). It shows the amount removed for each location found (in bytes) and the total removed (in MB). Before running, it will stop Explorer and all other running apps. When finished, a reboot is required the user must reboot to finish clearing any in-use temp files.

Thank you, but I have started a reinstallation in the meantime, and will remeber this suggestion for "next" time.