Arduino UNO won't connect to computer (I've already read the forums!)

I have looked through the forums and tried everything they suggested on the Getting started and troubleshooting pages.

Model number: Brand new right out of the box Arduino UNO (which I am most concerned about), as well as an older arduino uno and duemilanove Macbook pro 15" / White macbook 13" both with OSX 10.6.6 have yielded same results I've tried with two different USB cables. I've tried with and without an external power source as well as USB.

"Connect the Arduino board to your computer using the USB cable. The green power LED (labelled PWR) should go on."

This happens.

"If you're using the Arduino Uno or Arduino Mega 2560, a dialog box will appear telling you that a new network interface has been detected. Click "Network Preferences...", and when it opens, simply click "Apply". The Uno or Mega 2560 will show up as "Not Configured", but it's working properly. Quit System Preferences. "

This does not happen. When I go into Network preferences there is nothing to select and it is not possible to click on "Apply".

It goes without saying that the USB port does not appear under the Serial Port selection in the Arduino software.

As far as I understand neither the UNO nor the duemilanove requires a driver. I never used one before.

The older Arduinos both worked well at one point. Like the new UNO, I have tried them with different computers and USB cables. What I find especially strange is that when I connect the duemilanove to the computer via USB the green LED goes on, and also the TX and RX LEDs. Is this normal? I didn't notice it before.

I think it must be something with my computer, but am a bit perplexed because 2 days ago I was having no problems at all with the Duemilanove, and the new UNO seems to be dead on arrival. Any ideas? Mainly I want to know if I should go ahead and send the new UNO back, although it would be lovely to get them all running again.

Are you connecting to a USB Hub? UNO and OSX don’t always get along in that case. Since some of the ports on a Mac are actually on an internal hub, try all the other ports.

Look at System Profiler (refreshing when you connect or disconnect the Uno) to see if OSX sees anything.

Also, drop into the terminal and run “sudo dmesg” after connecting, to see if the kernel is giving any hints.

And the Duemilanove does require the FTDI drivers.