I've a Asus laptop with windows 8.1 pre-installed, I've managed to install Ubuntu alongside it, and for some days it worked fine. Today, out-of-the-blue, Ubuntu just goes black screen and I'm back at the grub menu to select one of my OS's, when I tried to boot to Ubuntu, it just says it cannot mount '/boot/efi', and it doesn't let me select none of the options ( one is to press S to bypass the mounting process and the other is to press M to manually correct the problem). If I go through the recovery mode, and try to start up normally, it let me bypass the mounting procedure and startup Ubuntu as usual.
How do I deactivate the mounting process at the startup? Or better yet, how do I solve the problem?