I just succesfully joined 4 laptops with Windows 7 to my domain. 3 of my domain controllers are running Win2k3 R2, and one is Win2k8. I didn't encounter any issues. The only issue I found was with printer drivers not working with windows 7.
It sounds like you have an underlying network connectivity problem. Is your laptop on the very same LAN as the domain controller? If not, you won't be able to join a new computer remotely to a domain while it's not on the same LAN.