Due appears as COM6 port but gives error "No device found on COM6" on upload

Just bought my DUE from Robot Shop, made in Italy. Same problem and the fix of re-setting works.

I am using the native USB which is faster anyway. I found when you reset that the COM port changes - look on Device Manager! It only changes once - for me from COM 16 to COM 15 and then it started working without the reset thing. So I am ok so far.