Windows network probem - network 2

I have four nodes on my network, they are all hooked up to the same switch and all of the computers can see each other except for one. The three that can see each other states that they are on the network "Network" and the fourth computer states that it is on network "Network 2". We had it working yesterday but today it stopped working and it can't see any of the other computers and can't seem to get it to work. I have restarted the system. Restarted the switch, disabled the network adapter and then enabled it. The system atleast has internet access but that doesn't help getting access to the other systems. The ip address goes along with the other ip addresses 193.168.16.x. Please anyone help.

What operating systems are in these computers?

What type of networking are you using Home or Work?

Is the Workgroup name the same on all computers?

We need lots more information to give you a good answer...