So you say the MCT can contact the printer with Canon media files, but can't get contact at all with third party files? Now that's weird. If I had say a generic USB network dongle I might give that a tray, maybe there's something with Bonjour. On Vista64 I couldn't get IPV6 to work at all, but IPV4 just fell into place, could be a router issue. Hmmm, might look at the router.
Or maybe the file is bogus. For the two media files and the two profiles I have from manufacturers, I would say those things had been pushed out the door pretty fast and possibly by people as confused as us.
I just let the printer calibrate its own media settings as in the video on the BC site, then ran a Spider Print profile which is not great but better than the canned ones. The manufacturers' canvas files had the head heights swipingly low, and the ink loads at least a notch too high for their own profiles. I think that's just another case of manu's putting DMax above all else, but I definitely prefer the lighter ink loads.