Windows Update Disabled (XP)

[ent]

I'm a Windows XP user who has always gotten virus updates and occasional patches from Microsoft.  Seemingly, on the very day that they announced the patch for the WannaCry malware, my Windows Update option stopped working.  I can view any other websites with IE8, but when I try to do a Windows update, I get the following error message:

      Internet Explorer cannot display the webpage

When I run MS Security Essentials (with its now 3-week old virus definitions), it finds nothing.

I downloaded and ran combofix, but it found nothing and fixed nothing.

When I run the free Malwarebytes, it repeatedly find this key:

     PUM.Optional.ProxyHijacker,
     HKU\S-1-5-18\SOFTWARE\MICROSOFT\WINDOWS\CURRENTVERSION\INTERNET SETTINGS|ProxyServer,
     http=127.0.0.1:5555, , [021061e0ccdd2610f72bd3308a796997]

I can delete the registry key, but it always comes back in a matter of hours.

Where should I go from here?

Thanks!

Edited June 22, 2017 by ent
bump after no response in 4 days

[ent]

UPDATE:  I just re-installed IE8 and it did not change anything.

UPDATE 2:  I managed to find a stand-alone executable at Microsoft that allowed me to install the WannaCry patch.  It seemed to work, but I still have the problem of being unable to run Windows Update and hence, unable to get virus updates and future fixes.  (And the problem of the re-appearing registry key.)

Does anyone have any suggestions?

Edited June 22, 2017 by ent
status update