The current setup we have is:

Citrix certificate server on a DMZ which passes authenticated users through to a citrix presentation server on our internal network.

That all works a treat, but I don't know exactly how, therefore troubleshooting why when I convert the presentation server to a vm image and fire it up live people can no longer login remotely.

I can only presume that there's somethign hardware specific that is either on the certificate server or the presentation server. Something like the certificate server looking at the MAC of the presentation server? I'm guessing at what it could be, but after looking through the settings on both servers I can't see anything obvious.

It's also difficult for me to find out exactly what the error was when we tried it as the physical server is back up and running again at the moment so that people can use it....