Failed install Vista 32 SP1 "Update..(KB973917)"

[jgirone]

Please excuse my virgin post for help if awkward or seemingly ignorant. Have gone through all the MS support articles I can find and have tried everything recommended aside from a clean Vista reinstall, I have been unable to substantially update for 8 mos, but continue to successfully automatically update all MS Office products. Over the past day a regular (non-security) update of .Net Framework 3.5 was installed after a recommended Clean up Utility was employed and I was able to narrow down the limiting update failure to remaining update installs ("blocking" the 30 or more others), to the above "Update..(KB973917)", even when downloaded & separately installed from the MS support download site.

Despite multiple "successful" System Update Readiness Tool" completions, followed by immediate restarts then attempted Update install, all done under "clean boot" conditions, with "Mal-Aware Bytes" uninstalled and Norton IS Ver. 17.7.0.12 clinically disabled, but still installed, I continue to receive the error on log review as follows:

Error details: Code 80073AA2

Update type: Important

Install this update to help strengthen authentication credentials in specific scenarios. After you install this item, you may have to restart your computer.

More information:
Microsoft Security Advisory (973811): Extended Protection for Authentication

There is no available information on that specific error code, except veiled references to potential third party interferences which is why I attempted it only under the above conditions described. Even though there was never a MacAfee product installed, I even tried their Product Removal Tool to no avail, with all removal attempt results given as "Do not exist".



So, at wits end can anyone help?

Joe