Server not found
I also had this problem and went the old version route, which worked. I am sure that it does have something to do with Firewalls. The old version needed permission from my firewall (Trend), the new one never asked.
Once I had the old version working for a day, I upgraded to v 5616, kept all my old settings and it actually requested permission to connect and has worked perfectly for three days now.
What is strange, is that the entries generated in the exception list for the firewall makes no mention of programs by name, but only says" this application is used by Weather watcher to download from…".