This most probably means that your computer either doesn't offer resource sharing or it has Winsock version 1 originally shipped with Windows 95. In the latter case, consider using nbtstat -A xxx.xxx.xxx.xxx instead, or upgrading to Winsock version 2. This limitation doesn't apply to viewing other computers' name tables (Winsock 1 works just as good as Winsock 2), nor to NetAudit (you can audit your own computer with it).
