usb and mountain lion

Hello,
I recently installed mountain lion on my macbook (model mid-2009) and the usb modem device is not available, /dev/tty.usbmodem does not.
I already try to install again usb drivers but it doesn't working.
Somebody has an idea for that ?

Thanks you

max

What Arduino?

For an arduino uno

When arduino is attached, when shows up under "usb" in "System Information"?

Make sure you attach the arduino before you launch system information.

Same thing! I have a Mac Book Pro with OSX 10.7.5 and even though I can see the arduino board when I go to system information, the fact is that when I try to upload the sketch it's not recognizing the serial port (tty/dev/usbmodem131) and Arduino IDE reports a Programmer not responding error. Please help!

mikita:
even though I can see the arduino board when I go to system information

What does system information say about it?