Windows update suddenly this month refused to run coming back with the red shield and ERROR CODE 8024800A
I tried a few things like SCF/Scannow but nothing worked except this:
Click on Start button, navigate to Accessories and Command Prompt
or Type: cmd
Right click on cmd in start menu and select 'Run as Administrator'
Type: net stop wuauserv
Type: ren c:\windows\SoftwareDistribution softwaredistribution.old
Type: net start wuauserv
Now download updates.You have deleted the history of the updates so it may be a while scanning.