Im running Ubuntu 15.04 on an SSD which is low on space so I decided to download my Steam games onto a seporate HDD which has only Steam games. I set the partition of that HDD to autostart in Disk Utility, and ever since I rebooted, GUI would not appear and I would only have a text console. After logging into the console, it tells me:
/usr/lib/update-notifier/update-motd-updates-available: 39: /usr/lib/update-notifier/update-motd-updates-available/: cannot create /var/lib/update-notifier/updates-available: Read-only file system
/usr/lib/update-notifier/update-motd-fsck-at-reboot: 33 /usr/lib/update-notifier/update-motd-fsck-at-reboot: cannot create /var/lib/update-notifier/fsck-at-reboot: Read-only file system
These 2 errors seem to be related to a drive being mounted as Read-only, however the drive that I applied the mount option to is not in any way a system drive, and has only Steam games on it.