Opening Mapped drive on 1 computer is slow

We have many computers in a Domain and all open all mapped drives quickly. We have 1 computer that opens all mapped drives quickly except for 1 mapped drive (which is on the same server as the other ones.) In researching I opened a command prompt and did a netstat – and found a TCP session attempted to start to a non-existant computer in the domain. I suspect that after about 30 seconds or more, it times out and then the folder opens on the server. I’m trying to find out where the reference to that non-existant computer name is so I can remove it and hopefully solve the problem. I’ve searched for that computer name in the registry and it doesn’t show up. Any ideas where else to look?
Thanks.