I pulled a new "My Passport" drive out of the box last night and spent several hours trying to figure out how to write to it. Finally learned that if I reformatted the disk as FAT32 it would work (really?!). So i did that and can now write to it from both the mac and parallels (but should I really have to do that). That got me by last night, but today I have a friend's external USB hard drive that I'm presuming has NTFS that I can't write to with either my mac os, or windows 8.1 on parallels (Parallels desktop 10). I can't really reformat his hard drive (and it seems like I shouldn't really have to do this anyway, right?). It's a bit like buying a new Lexus then ripping out the seats and replacing them with lawn chairs. Don't make me get out the lawn chairs! I found this article (http://forum.parallels.com/threads/external-usb-ntfs-drive-writable-by-parallels.4903/) from "the long long ago" which talks about unmounting the drive from the mac and then somehow reconnecting it with Parallels using "the USB connection thingy in the lower right side of the parallels window" to connect to the hard drive, but I can't figure out what the "USB connection thingy" is (or whether I even have one in parallels 10/windows 8.1). Any help would be greatly appreciated.