I am having the same issue on WinXP;
so should I change
#ifdef CDC_ENABLED
#define DEVICE_CLASS 0x02
#else
#define DEVICE_CLASS 0x00
#endif
to
#ifdef CDC_ENABLED
#define DEVICE_CLASS 0x00
#else
#define DEVICE_CLASS 0x00
#endif
in arduino-1.5.1r2\hardware\arduino\sam\cores\arduino\USB\USBCore.cpp?