Windows vista does not find a printer in a network

In my job we have windows 2000, XP and the newest two computers are Vista. The newest one (4 days old) is not printing any more. It used to, but not now. The printer is connected to a computer in another cubicle. All other computers print. Except for this one. When I installed it I printed out a test page and it did fine. Since yesterday my boss could not print anything. I tried to add a printer, but the computer sees no other computers in the network, only the other vista computer. When I try to look for the computer with the printer, it does not show. Anybody has an idea of what's going on?

I don't know if you need this anymore, but I had the same problem and found THIS to be the solution.