You have to have some sort of configuration or software blocking your friend from accessing your hamachi server.
Common sources include windows firewall, virus protection utilities (Norton firewall for example) and many many others... If you want to get it working, you'll need to find out what's getting in the way first.
Both of us use AVG Free as AV, where the firewall is deactivated, and we've both poked holes in the Windows firewall for Mr. Java to come through.
Here's the server output if it makes you any wiser.
We've tried to run the server on countless ports, without any progress, yet it somehow works when I run it.