I'm afraid this is a bug in your system's bios. Grub uses it to read from the keyboard, and if that keyboard happens to be USB, then it is up to the bios to manage all of that.
Grub does have its own USB driver that you can force it to use instead of the bios. This might be a way for you to work around the bug. ** Changed in: grub2 (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1537917 Title: grub does not respond to keyboard if usb drive is not present To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1537917/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs