Hi Michael,
Error message 1231 means that The network location cannot be reached.
This means that the compute node is not able to write to the location on the headnode it wants. This might be a firewall or a name resolution issue.
A good test would be to login on the compute node having the problem as the user who was running clusrun and then try to see if you can write to a share on the headnode from that compute node.
See if you can write a file to \\EMSWHPCM1\CCpSpoolDir\ from the compute node.
If you cannot write to a share on the headnode, you might want to do a nslookup for the headnode on the compute node to see that the server name gets resolved correctly.
sayantan