I would really like to find ouot what is causing this. Not having direct control over the computersm which are having this problem, and they are a small group makes it difficult.
What triggered it is more than likely the added ports and new IP address the server has.
This suggests firewall, or anit-virus. Possibly the ISP blocking a specific set of ports. It could be security software. By the way, Norton and McAfee patch the Windows kernel as part of thier installation. Once that patch is done, it cannot be undone. Removing the software does not remove the patch.
That aside, it would interesting to see what commonalities there are in these systems, if any.
I cannot duplicate this issue no matter when I try or where I try from (home or work). It is not the server itself causing this. If it was, it would effect everyone equally.