After having had trouble with setting up samba shares (pointing to files/folders on a windows macihine) my suggestion would be to set up some /mnt shares using autofs as described in this thread. I appreciate this may be doing things the other way round, so why not connect the usb hdd’s to your windows machine rather than the vero ? Also did you take a look at the windows logs in event viewer ? Sounds like a permissions/credentials issue. You should also perhaps take a look at the samba log file on the vero when you get these access failures by windows.