Vista - WSUS 3.0 SP1 - Few Clients not Reporting

I have 50 computers on my network SBS2003 network. Of the 50 computers 3 are
not reporting to the WSUS server.

2 computers are XP sp3 and the other is Vista sp1

I have done everything I can think of to get the Vista machine to report.
Since the Vista machine is mine I can work on this one the easiest.

1. I thought the problem was initially duplicate SID, so I ran NewSID.
2. I've deleted the softwaredistribution folder and ran the
/resetauthorization
3. I have verified that the GPO is applying on the computer
4. Cleaned the registry - SUSClientID
5. Removed computer from domain and re-joined
6. Deleted the virtual direcory in IIS and re-created.

BTW - the ports are 853 and 8531 for SSL. The default website does have a
SelfUpdate virtual directory.

Any ideas would be greatly appreciated.

Thank you
Nick