XP Repair with CD

I know about the repair you can do with the XP disk, my question is when you do this you will then have a problem with windows update, you can download updates but windows will not install them. I’ve been to Microsoft and did what they tell you to do, turn off automatic services reinstall windowsupdate 3.1 turn on the services again, reboot and all that but It don’t work. Any other fixes you might know about.
Thanks