I check the address xxx.xxx.xxx.xxx by both NBScan and nbtstat and get no results. The person to whose computer this address is assigned checks the same address (his own) and gets his own computer's name table. Why can he see it and I can't?
There is a firewall or some other packet-filtering device between his computer and your computer. Certain packets may be rejected because of the firewall settings. Also, some Internet Service Providers filter packets without informing their customers. If that's the case, you may want to audit the network from a different account.