I get the GRUB menu, hit 'ubuntu', and then it cuts to a black screen with a blinking cursor. After ~a minute, it gives this message:

Gave up waiting for root device. Commone Porlbmes:
    - boot args (cat /proc/cmdline)
        - check rootdelay= (did the system wait long enough?)
        - check root= (did the system wait for the right device?)
    - missing modules (cat /proc/modules; ls /dev)
ALERT! /dev/disk/by-uuid/7987ff8c-9aa4-4e36-8b43-32d4ac1aa623 does not exist
dropping to shell!

and it shows a BusyBox command prompt.

My Lenovo T530 has a 16gb SSD, where Ubuntu was installed, and a 500gb HDD, and a NVIDIA NVS 5400M Graphics with Optimus Technology, 1GB DDR3 Memory Graphics card.

I installed both the OS and GRUB on the SSD.