Can’t view network computers

I have a Win98 machine which suddenly stopped allowing other computers on the network to use the shared software on that computer (It is the server for a software). When I go to “Network Neighborhood”, I only see myself, but if I search for a computer, I can find any of them. I also have no problem connecting to the internet or e-mail, and connecting to folders and programs on our server. However, nobody can connect to the shared software. I have checked all of the protocalls and rebooted, I even scanned for viruses, still nothing. Why is this? Please help ASAP!!! Thanks!