Serial port already in use


I'm getting the "Serial port already in use" when I try to upload a new Sketch to my Arduino Duemilanove 328.

I'm using OSX and have had no problems before. The problems only began when I tried to upload a sketch to a different Duemilanove (I have 2). Now I can contact neither.

The boards connect fine from my Windows computer. Both are in working order. I've tried pressing the reset button in different places during the upload but to no avail. I have no other software accessing the USB ports.

Apologies if this has been asked and answered before, I couldn't find any soutions to help me. Any guidance would be greatly appreciated.

Thank you.

You should be able to use any number of arduinos you like on a Mac, I do.

It sounds like there may be something wrong with the Java install. You could try the old Microsoft trick of uninstalling the java (or whole package) and then re installing it again.