win7Pro 32 bit KB2971850 (only) update Error 800B0100 (son's laptop)

Very odd - it found that error in the middle of the run - but there's no mention of it in the summary at the end.
The summary is also devoid of the usual detail, saying only

Code:

POQ 92 ends.
2014-10-14 14:42:17, Info                  CSI    000001d8 [SR] Verify complete
2014-10-14 14:42:17, Info                  CSI    000001d9 [SR] Repairing 1 components
2014-10-14 14:42:17, Info                  CSI    000001da [SR] Beginning Verify and Repair transaction
2014-10-14 14:42:17, Info                  CSI    000001db Repair results created:

I'll post a fix for that error later and we'll see what it says about it then.

Can't hurt!

Looks good to me - I'd say try a new Check for Updates, then try to install ONLY the oldest found update, and see what happens.

If it fails, post the KBnumber and the Error code
If it's OK, the try installing the rest.

I'll justpost a few details, in case they're of any use to someone with a similar issue.

Did a manual "Windows Update" - which looked real bad, as it failed: "Windows could not search for a new update", with error code 80248014.

After briefly hanging my head in despair, I rebooted & tried again.
It now didn't immediately fail, but worryingly had gone back to the message that I'd never checked for windows update before (lie!).

But it then found 18 updates, including the my key one, KB2971850.

Deselected all but that one, and it downloaded it, prepared to install, created a restore point and installed OK.
I checked in the list of installed updates, and yes, there it was. Yo!

I then installed just the latest MS software removal tool in isolation - success - after which I let the remaining 16 go. Also fine - and yes, all were there in the list of installed updates after.

So as a final check, I did a manual update again - No updates found.

Success

Many thanks for being a star and sticking with me

An afterthought;

I did wonder if after the earlier SFC /SCANNOW fails, whether a reboot and another SFC /SCANNOW might have reported a clear result - which I think was the case this time.
I have NO idea why that could be/should be/was the case though...

It's very rare for SFC to fix anything more on a second scan than it could on the first, unless there's outside intervention of some kind. It's always possible that there was some kind of interference on the first scan (say from an AV) which wasn't present on the second.
Whatever - at least you're up and running again!

Good luck!