Files required to use windows Update are no longer registered

I have 8 Dell dual core GX755 machines that have all been imaged with the
same Windows XP SP2 image from our network. 4 machines update fine, 4
machines receive the Files required to use windows update are no longer
registered and registering them does not work. We have tried every fix and
re-registering of stuff that has been listed in ALL of these posts. 3 of the
machines now work but one is still giving us grief. We have totally reimaged
it 3 times but get the continued error. Have run ALL of the known fixes over
and over and over again. And yes we restart everytime! All machines are
exactly the same. The updates work until the machines are joined to the
domain. They are all going to the same domain and receiving the same policy.
This is driving us nuts. Anyone have any ideas! What heck is going on!