Sounds like an issue with your config... and nothing to do with the D-Link. Since it was working before, this further reinforces the fact that it's something to do with your computer and not your camera. That is probably why D-Link wants to charge you for support... because the problem isn't with their hardware.
How old is this computer that you have just upgraded to SP2? It might be time for a fresh load of the OS. Oh and check the Windows firewall settings... your firewall could very well be blocking access to your camera.