Windows Update Error 80073712

The CheckSUR log shows the following summary...

Code:

Summary:
Seconds executed: 640
 Found 166 errors
 Fixed 160 errors
  CSI Manifest Missing Total count: 4
  Fixed: CSI Manifest Missing.  Total count: 4
  CSI Manifest and S256H Do Not Match Total count: 1
  CSI Missing Component Key Total count: 6
  Fixed: CSI Missing Component Key.  Total count: 6
  CSI Missing Pinned Component Key Total count: 6
  Fixed: CSI Missing Pinned Component Key.  Total count: 6
  CSI Missing Deployment Key Total count: 2
  CSI Missing Identity Total count: 23
  Fixed: CSI Missing Identity.  Total count: 23
  CSI Corrupt Identity Total count: 4
  Fixed: CSI Corrupt Identity.  Total count: 4
  CSI Missing C Mark Total count: 31
  Fixed: CSI Missing C Mark.  Total count: 31
  CSI C Mark Deployment Missing Total count: 2
  CSI Located Replacement: Invalid (S256H) Total count: 13
  CSI F Mark Value Wrong Total count: 1
  Fixed: CSI F Mark Value Wrong.  Total count: 1
  CSI F Mark Missing Total count: 91
  Fixed: CSI F Mark Missing.  Total count: 91
  CBS Registry Error Total count: 1
Unavailable repair files:
 winsxs\manifests\amd64_system.data.oracleclient_b77a5c561934e089_6.1.7600.16385_none_800ff37184f818a9.manifest

There are a large variety of errors there - much more than we normally see. It makes me wonder what could have caused them all.
I suspect that the root cause is a problem with RAM.
You need to test your RAM with MemTest86+ - RAM - Test with Memtest86+ - run at least 3 full passes. Even one error means that there is a problem which must be addressed.

I don't think there's much point in attempting to fix this until we're sure that any fix is going to stay fixed

Very possibly - does the RAM test out OK now?