I have 2 external hard drives I tried to use on my Surface Pro. One is a Western Digital My Passport that shows up when I connect, and I can read/write/copy etc but it won't let me eject it. When I try to eject it by right clicking the option isn't there, and if I try it in the Finder the eject button is grayed out. Had to turn off my Surface before disconnecting. My portable Toshiba hard drive just keeps opening a window when connected and keeps dinging when it does so, like it's trying to open the hard drive but it doesn't work. Then it causes my micro SD card to not show up. It will just keep opening windows and dinging until I shut off the computer to eject (and I think it causes issues with my WiFi too.) I also have a 32GB thumb drive that I erased and formatted on my MacBook Pro with exFAT, that works fine in the Surface. The two drives are older and have been formatted for Macs, I'm just not sure what formats they are. Does this sound like an issue with my Surface Pro? Or is it possibly an issue with my hard drives or the way they were formatted? Anybody else come across these issues?