I have host XP running guest Vista. I setup vista using host interface networking and the Intel PRO NIC (supported by vista at boot time).
Later I changed the VM to use NAT networking instead of Host Interface networking. When I boot vista, it's networking gets all messed up and it doesn't see the internet.
It appears that the guest still thinks it's IP address is the one from Host Interface mode and the NAT emulation DHCP didn't seem to give vista the NAT 10.0.2.15 address.
I tried many things to get guest vista to work with NAT, and the only thing I was able to get to work was deleting the Intel PRO NIC adapter and rebooting. Upon reboot, vista reinstalled the NIC and then NAT mode seems to be working fine.
There MUST be a better way to "fix" guest vista after changing from Host Interface mode to NAT mode. I'm wondering if there's a bug in the VBox NAT DHCP handling that breaks if the guest OS asks for a previous IP address that the NAT DHCP doesn't expect.
Bit.