For reference, I've had some experience with Arduino before. Anyway, I just got the Due the other day and I wanted to test out the new USB functionality, namely the fact that it can act as a USB mouse and keyboard. Or at least that's what I thought, because when I load up one of the example sketches, such as KeyboardSerial, there is no output from the Due. I've tried running that sketch from the programming port as well as the native USB one, but to no avail. Is there something I'm not understanding?
So eventually, just plugging the Arduino in using the Native USB port made my PC BSOD, but that has since been fixed. Also, when the Due is using the Programming port, it shows up as COM4. However, when I plug in the native USB port, the Serial Port box is greyed out.
Interestingly enough, I COULD get it to be seen as a keyboard/mouse on my Linux box, but not on Windows.