Thank you Ed again.
The affected NT Server regained its name yesterday night,when probably the suspicious machine's owner turned the machine off, I guess the assumption two machine share the same NetBIOS Name would be right.(Maybe he must have found the error message as soon as turn on his PC this morning.)

Anyway our entriprise Network(NT) speread all over the country including four major site as hundreds Kilometers as away . I want to pick up the trouble-making PC by all means. Is it possible ? (;All employees are strongly recommended to follow the naming convention configuring his NetBIOS NAME. But he probably disobeyed)

And regarding your suggestion to use IP address, would you give me an example?
That is to say ,if the original name is FirstName and Service name is SERVE users would do like this \\FirstName\SERVE to use its resource. I don't know what to do first if the NetBIOS Conflict accur again.

REGARDS