After many update installation attempts on both computers through the Windows Update application and through manual installation attempts of the KB3000850, I only achieved installation failures. Here is what worked for my machines, in order of task performed:
- turn off all non-critical services via msconfig.exe
- restart computer
- open a Command Prompt with administrator privileges, run sfc /scannow (it found OS corrupted files on all my computers)
- manually install KB3000850 (use downloaded file from Microsoft)
- reboot (note, reboot took quite a while as Windows was configuring OS)
- Check Windows update again to make sure it has installed. Also check for any more windows updates and install them.
- turn back on services that where turned off during update preparation
- turn back on Classic Shell