Mapping non Domain drives

We have a few Isilon clustered storage systems at work that are on the
workgroup and not on the domain. I can connect to them and map to them but
here's the strange thing.

When I map to the name, for example, Isilon-a-1, then reboot. The connection
can not be restored and I can not browse that mapped drive. I then have to
disconnect it and browse to it again.

If I go to the IP of the cluster and map it that way, I can reboot all I
want and it maintains the mapping.

Is this a NetBios issue? I have enabled it and tried different services and
network settings without much success.

I am running Ultimate RTM

Thanks