I have a Windows 7 VirtualBox VM (64 bit, 8 GB) on a Snow Leopard host (64 bit, 24 GB). It works fine until I connect via Microsoft Mesh.
When I connect via Mesh remote desktop, the VM crashes about one or two minutes after the connection has been established. It doesn't answer to pings (from the host and from other machines in the network) and no RDC connections (from other Windows machines in the network where Mesh works) are possible.
Update: I have now tried connecting to the VM using Mesh while watching the screen of the VM. What happens is that a minute after the Mesh connection was established, Windows just freezes up. Sending ctrl-alt-del using VirtualBox doesn't help and the machine doesn't respond to pings any more.