RDP connection error when connecting to a Windows 2000 server.

I have a vista user who used to be able to rdp to our windows 2000 server and
all of a sudden today he's getting the following error: This computer can't
connect to the remote computer. The connection was lost due to a network
error.

He can still RDP to our SBS 2003 server and once there can then RDP to the
2000 server. This was working then just stopped. I haven't changed anything
on the network. Anyone have ideas or have had this happen to them?

I have tried connecting via Administrator and tried deleting the mslicensing
key in the registry on his vista (I had to restore it because I got a
licensing error).