I would try doing this the next time this happens and nothing is working.
Reboot to safe mode.
Go into Task Manager > Services > cryptsvc > stop service
now go to C:/Windows and delete the Software Distribution folder. This is where updates are temporarily stored after downloading them.
Now go to C:/Windows/System32 and delete the folder Catroot2.
Go to folder CodeIntegrity and delete the file bootcat.cache.
Finally delete WindowsUpdate.log inside C:/Windows.
Now reboot.
Reregister the Windows Update Service. Here is a batch file that will run all the necessary commands to do that:
http://www.sevenforums.com/attachments/ ... istory.batThe commands are as follows:
net stop wuauserv
regsvr32 /s wuaueng.dll
regsvr32 /s wuaueng1.dll
regsvr32 /s atl.dll
regsvr32 /s wups.dll
regsvr32 /s wups2.dll
regsvr32 /s wuweb.dll
regsvr32 /s wucltui.dll
net start wuauserv
Reboot the computer.
If this is Windows 7 or earlier, download the relevant Windows System Update Readiness Tool and run it.
Reboot.
Now try again.