I have had a couple of machines this year that have stuttered a little when using Microsoft Windows Update on some older system (pre Service Pack 2) following a system recovery.
In both cases the fix was stop the update processes, re-register processes in the registry and then re-start the auto update process.
I’m not sure what ‘breaks’ the process but, in my case, both systems had a recovery that took the OS back to XP Sp1.
The actions to fix this were:
Type: net.exe stop wuauserv
Next register the individual process by typing in the following (press enter after each one):
Finally re-start the update process.
net.exe start wuauserv
If all is well you should now be able to run the Windows Update process from the usual icon via Start.