Connecting ethernet shield to Arduino Uno results in serial port not found

[system]

Hi everyone,

Has anyone encountered this before? When uploading an example such as Blink, my Arduino Uno by itself works as expected. However, when I connect the ethernet shield to it, I am unable to upload the example Blink to the Arduino. Please see attachment (Arduino_Blink.png). The error says:

Serial port '/dev/ttyACM0' not found. Did you select the right one from the Tools > Serial Port menu?

processing.app.SerialNotFoundException: Serial port '/dev/ttyACM0' not found. Did you select the right one from the Tools > Serial Port menu?

It also gives the same error when I try to upload the example SimplePost from the Twitter library found here: Arduino Playground - Twitter Library.

I don't think there is anything wrong with the serial port because it works without the ethernet shield connected to the arduino unless it unexpectedly changed (??). When I do try to click Tools > Serial Port, I don't remember getting any options..

Any recommendations/thoughts are greatly appreciated. I really want to be able to tweet from the Arduino.. That is my goal. XD Thank you!

[system]

I think I found out what the problem was: I set the IP address of the Arduino device to the same one that my laptop had.. Changing the IP address of the Arduino device to another IP seemed to have solved the problem. However, now that I think about it, I had unplugged my ethernet cable from my laptop and chopped it into the ethernet shield, so the IP address set to the laptop should have been available...

Durrr... Well at least I am making progress.