Problems with OS X 10.7.2 (Lion) "port already in use"

Hi there!

I'm new here and absolutely new to arduino. While setting up my arduino environmet yesterday, I hat the problem when I wanted to connect my MEGA2560 to the USB-Port: "port already in use".

To fix it I had to create a folder "sudo mkdir -p /var/lock" and set the priviliges for it "sudo chmod 0777 /var/lock".

Maybe someone else has the same problem. I was looking for hours in the internet to find it.