Well !!
Sometimes "MountedDevices Host" works and sometimes not.
With Win7PE that working on one laptop Asus but not on my EEPC Asus and 2 other towers I have
And with Gena doesn't work at all, sometimes it's C: and sometimes D: or F: or E: ...
I have Win7PE and Gena on the same UDB Key and boot them with Grub4dos.
Maybe I'm doing something wrong but I do not see what.
PS(maybe a lead for this problem, all PCs where "MountedDevices Host" doesn't work have a SSD)