"Windows Update is downloading.." and hangs

Trying to run Windows Update for the first time on a pc that I have just
reinstalled the XP Home Edition OS - installed it on top of itself. Reloaded
many apps. All is working except for Windows Update. It tells me that I
need to load a new version of Windows update. It checks for the latest
version and once it gets it, it says to click on INSTALL NOW. THen the
message "WIndows Update is downloading and installing the updated software"
appears. Then it says "Downloading 100%...", then it says "Registering
100%..." and just hangs. Nothing happens from here on out. So consequently
I cannot run Windows Update to check for critical updates. Anyone have a
suggestion?