Check this option:
LAN settings -> select "Internet protocol ( TCP/IP )" -> Properties button -> Advanced button -> WINS tab
"Enable NetBios over TCP/IP" should be selected.
If it doesn't help, check firewall to allow "Files and Printer sharing".
However this protocol is deprecated, I recommend you to update to LanTalk NET
http://www.cezeo.com/products/lantalk-net/