Computer runs Windows 7 Professional SP1
Windows Update for 13 January 2015:
KB2901983 installs .NET 4.5.2 - fails with error code 13EC unknown error
KB890830 installs Windows Malicious Software Removal Tool - fails with code 643 unknown error
Fixit 5023 does not stop the above failures.
KB947821 System Update Readiness Tool also failed to install.