While struggling with a Windows 10 EFI installation on a GPT partitioned HDD ( https://forums.mydigitallife.net/threads/71409-Installing-Windows-7-after-Windows-10-(dual-boot) ) I discovered something dreadful. Pressing SHIFT+10 to bring up the command prompt window gives you a crippled command prompt in which pressing the '\' key shows a '#' character on screen. Impossible to navigate the file structure. E.G. cd D:\backup turns into cd D:#backup I really want to kill someone now.