You should do this just to be sure that games will work correctly for Hamachi play. This will make games use the Hamachi network interface before other network interfaces.
Windows XP (Make sure your a administrator user)
- Click on Start > Control Panel > Network Connections.
- Click Advanced on the file menu (after tools).
- If you cant see it click Alt on the keyboard.
- Move Hamachi to the top of the list. Click Ok. You may need to restart your computer now.
http://www.youtube.com/watch?v=o4QdCxk_Z1I
Vista (Make sure your a administrator user)
- Click on Start > Control Panel > Network and Internet > Network and Sharing Center.
- Click Manage network connections. New window should come up (Network and Internet > Network Connections)
- At this screen hit the Alt key on your keyboard to make the File menu come up.
- Click Advanced on the file menu (after tools). Go to Advanced Settings will give Network Adapters & Bindings Order.
- Click Continue if UAC comes up. Move Hamachi to the top of the Connections list and click OK.
- You may need to restart your computer now.
http://www.youtube.com/watch?v=rQkJiUkKypo
Source: http://wiki.rtsu.net/Hamachi_Fix
Via BFWGaming