Give this a try and see if it solves the problem………
Go to Start>Run and key in each of these commands, one at a time, clicking
on OK or hitting ENTER after each command and then clicking on OK in the
RegSvr32 dialogue box:
regsvr32 softpub.dll
regsvr32 mssip32.dll
regsvr32 initpki.dll
regsvr32 wintrust.dll
Restart and see if you can now successfully use Windows Update site.