I'm getting the exact same error trying to (re-)verify my genuine-article DB Pro CD.
I suddenly started getting an annoying blank white window appearing on top of my editor screen, which seems to be some kind of TGC advertising window. That has never happened before today, and I've been using DB Pro since August 2003.
Thought DB Pro might have somehow forgotten it was fully registered. Apparently an advertising window does appear if you're a free user, but I've never seen it before because I've always owned the CD version.
I tried to re-activate my copy via the CD but just kept getting that message about failing to contact the server. Disabled my firewall, too, but it made no difference.
TBC