I search the forums and I can't find a solution for me yet. I run on windows 7 64 bit, I use microsoft security essentials for AV and I use default windows firewall.
I can't ping other people even though we have a direct tunnel, but other peopel can ping me. This problem only applies to my computer, even though my sister uses the same modem she does not have this problem.
I've seen where other people suggest changing router settings that deal with blocking pings from WAN (Wide Area Network, i.e. the internet). But I would not think that such settings would matter to Hamachi connections. My guess is that the computers that cannot be pinged have their firewall setup to block pings. This firewall could be one built into the operation system (OS) or one that is a part of a security suite.
For the Windows Vista OS and above, it is possible to set the Hamachi network connection to the Home network type and still have the OS firewall block pings. Here is a link to some info on Vista's settings: