Hamachi:McAfee Internet Security Suite 2007
All you have to do is *UNINSTALL* two components of McAfee Internet Security Suite 2007. They are:
1) SPAM Killer 2) Privacy service
It's important to UNINSTALL them, not only DISABLE them in Security Center. Just disabling doesn't work. Even when disabled, they still interfere with Hamachi's connectivity.
Go to Control Panel > Add/Remove Programs > Select McAfee and choose those two components to uninstall. Reboot and run Hamachi,