network neighbourhood not displaying ite

am using win 98 SE , am not able to browse network, till yesterday it was fine. now when i go to network nieghbourhood, am not seeing any workgroups.

but at start> run when i gava a command \\ am able to browse that system . i can ping to every system, but itz not getting on network neighbourhood. i installed NetBEUI Protocol. problem still persist.

i checked for virus also ?
same problem is happening with few other machines.

what could have gone wrong ??