Try reverting to an older version of Hamachi. Newer isn't always better.

I did try an older version of Hamachi! It says something like, "Hamachi server refused the connection" (I don't remember exactly). It asks for an update. And the other guys are using the new versions, and they work. And I can play Quake perfectly fine through Hamachi... And in Heroes, the IP address is entered correctly – using Hamachi, but for some reason, it can't find the servers (and they can't find me either)...

Added after 8 minutes
Another interesting fact that I can't quite make sense of:

While digging through all the settings, trying to find the problem, I disabled the DSNP Client and Network Connections – all connections, of course, went down. At that time, I had Heroes minimized, with the TCP/IP tab open. When I turned everything back on, the connections were restored, and when I opened Heroes, I saw a miracle – it found the created server (and, as it should, even without entering its IP address, it found it itself)... We even played normally. But on the second attempt to find the server, the same problem occurred again – IP not found....

What could this be?!?!?