Hello, I'm kind of a newbie in this forum so I beg your pardon if I'm missing anything, but I can't find anything refering to my problem. I write as I have a problem configuring a specific USB device: a datalogger which I suppose it's working as it works as expected (certified) in any Windows OS (XP to 8.x 32or64). I'm on a MacBook Pro, with Parallels installed. 1) I created a virtual machine with Windows 8.1, everything fine, but - I run the Win 8.1 virtual machine - I attach the USB device - Parallels asks me if I want it connected to Mac or Windows, I choose Windows - Most of the times the virtual machine locks and I have to kill it - when it desn't lock I can't even see the USB device in Windows device manager 2) I created a physical partition on my HD with BootCamp, in which I installed Windows 8.1 - I run the physical partition - the USB device (datalogger) works fine 3) I created a virtual machine upon the physical BootCamp Windows 8.1 partition - I run the virtual machine - the USB device (datalogger) works fine On one side I can understand what changes between case 1 and case 2. I can't understand what's the difference between case 1 and 3. Do you have any solution, fix, advice, checklist, documentation, whatever to help me? Thanks a million! Best regards