My case appears simple but something keeps bothering me.

I am running Ubuntu 10 as a guest using VBOx with the host being an iMac, I am using a bridged network adaptor and a wired network. I am able to do file transfer using gftp between host and guest without any problem, I am also able to ping from guest to host. My problem is, when I click on network in Ubuntu, it only shows me the host computer, the guest is not seen at all. Neither can I ping from the host to the guest.

Does anybody have an idea? I am sure the solution is probably very simple, I am not a network expert.