Paulo74:
A solution (at least for Windows users): plug your Adruino AND WAIT!On my laptop it takes exactly 3 minutes to let the COM port appearing in the menu. On a friend desktop, near to 5 minutes! But after it's working.
I guess the reason is a Windows update
This does not work for me. The only thing which is working is to downgrade to v1.6.11. (All later versions appear to have same issue)