I installed Ubuntu 18.04 on Alienware 17 R4. After the installation, I got an offer to restart the system. I clicked restart and nothing happened. And after force reboot of the system, Ubuntu can't boot. What's the problem? I used instruction: https://github.com/stormhart/dev-journal/wiki/Alienware-17-R4:-Dual-Boot-Windows-10---Ubuntu-16.04 Characteristics: - Intel Core i7 7700HQ 2800 MHz - 16Gb - NVIDIA GeForce GTX 1070 - 256Gb SSD