Today my Toad->Teradata connectivity works just fine. Toad connected to the database in about two seconds.. Clearly it's a server-side issue.
Please don't spend any more time with this issue. I'll work with the server support folks. They're new to the server and Teradata so it'll be a learning exercise for them too.
If I find out they changed a setting or something I'll post it here.
Thanks for your suggestions.
John