Windows 2000 PC can’t see PTP network

All of a sudden, my notebook PC can’t see the small (3 computer) peer to peer network to which it’s attached. The error message when I click on the workgroup is “workgroupname is not accessible. The network name cannot be found.” This computer had been working fine for months, but….
Notes: I am using Netbeui for the LAN. I can ping other sites using TCP/IP. Other PC’s on the LAN can see the Notebook.

Thanks for any help.