LOG IN NETWORK HARD DRIVE

I am using a network hard drive as a redundance system for a file server (file01). If the file server goes down i will change the name or/and IP address in the network hard drive (iomega) and user will be able to grab the files.
The client is using windows XP pro and the funny things is, i am able to access the new file server via IP address \\10.55.253.51, but if i try to access via \\file01 it does not allow me to access saying that the account is not authorized to log in from this station.
I am able to access \\file01 if i log in to the local computer instead of the domain.
I am also able to see the files from a linux server.

I know this is a problem of authentication but do someone knows how to fix it?

Thanks