I especially enjoy the comments from the Microsoft technical support folks. They are really trying to help. Like this comment. The key question comes at the end of his post.
You may update the BIOS and the hardware drivers first.
After that, I would like to suggest you disable the antivirus program and try to install the update KB977074 in Clean Boot manually again.
Here are the download links for the update KB977074:
Update KB977074 for Windows 7 32-bit: http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=19e12856-4808-4fbf-b5c9-2dac4bbb48b6
Update KB977074 for Windows 7 64-bit: http://www.microsoft.com/downloads/details.aspx?familyid=86B3EDE2-84EF-44A0-8084-D65AF65482BE&displaylang=en
Does it work?