I'm having a similar problem. I just got a new machine at work (six years into the two year upgrade cycle, but that's another story), and I can't for the life of me get the registration to work.
I too am getting the dreaded "HTTP Protocol Error. 407 Proxy Authentication". Our internal proxy uses port 8080. It's supposed
to be a transparent proxy, of course, so I "shouldn't have to do anything". I've updated the Options->Configure TCC->Internet, and tried again, with no luck. I've checked the updated TCMD.INI file, and proxy/proxyuser/proxypassword all look good, but then the 407 error is replaced with " Connection timed out". I'm not sure whether that it progress or not.
I ran Help->Updates, and my 13.03 version found, and successfully installed, version 13.04.63. It can download 11.19MB of updates, but it times out trying to register. After the update installation, it returns to the 407 proxy error; after re-entering the proxy credentials, it's back to " Connection timed out".
IT claims that since the update works, it's not the proxy, and say I've got to deal with the vendor. Changing the proxy is not an option. I've still got my old installation backed up; is there any way that I can scavenge the key to restore my registration somewhere? Or because that key be mapped to the hardware of the old PC? I read in the thread http://jpsoft.com/forums/threads/timeout-during-registration.2972/
that it's possible to get a manual key if I email you guys my registration credentials (I'll have to dig up that email). Assuming I can, I have another question. Supposedly, we're migrating from 16 bit XP to 32 bit Windows 7 in the "near future" (which could be 3 months or 5 years, who knows?). I assume that I'll have to go through this nonsense again?