Atropos7, Thanks for your reply.
Excellent - now we're getting somewhere. Everything from secure.newdream.net is aborted. It also explains why page renders take forever. Each aborted call lasts for many seconds. Unfortunately, as I said, it happens on all browsers, not just firefox.
I also checked it out on my wife's computer. Hers has no problem with it.
When I go to secure.newdream.net directly, I get a screen as quoted below.
Of course, once I clicked 'Continue to Site' all problems resolved. Nevertheless, dynDNS is suggesting that secure.newdream.net is harboring known spyware. Someone at DH might want to take that up with the folks at dynDNS.com. I've disabled the 'DYN Internet Guide' in my dynDNS systray app. Now things resolve as expected.