MS Updates hanging

I have 4 PC running XP Pro. Over the weekend I ran the
updates for SP2 and the .NET patch. Two of the machines
completed the updates fine. However I had a power failure
which affected 2 PC's. One had completed SP2 OK but was
in the middle of the .NET update. The Second was in the
middle of the SP2 update.

Now when I try to complete these two updates they just
hang at the 'initializing installation...' state.

I downloaded the SP2 update and ran this on the second
PC. However this now hangs at the 'Running process after
install' state.

Any help would be appreciated.