Computer Stops Seeing Other Computers on Network – Troubleshooting

I'm running Ubuntu 11.04.

Sometimes my computer stops seeing the names of the other computers on my network.

So I can no longer log into another computer by typing the hosting name

e.g. ssh me@secondcomputer.local

I can still log in using the local network IP address.

How can I get the first way to work again without rebooting? I know this problem is local to the computer.

The other computers on my network can still see one another. But they can no longer see the computer I'm working on, not even by local ip address.