Startup error with xserver-xorg-core

[wolfman]

Press the "Shift key" as soon as it starts booting!.

See this also:

How to show grub menu in Ubuntu with only a single OS installed

MAKE A BACKUP COPY OF THE GRUB FILE BEFORE YOU START, IF WHEN YOU RUN "SUDO UPDATE-GRUB" AFTER AND IT FAILS, REPLACE THE FILE YOU CHANGED WITH THE ORIGINAL COPY!. WARNING, DO NOT TRY AND EDIT THE "GRUB" FILE USING LIBREOFFICE, ONLY USE THE DEFAULT TEXT EDITOR LIKE PLUMA!. ONLY CONTINUE IF YOU ARE CERTAIN EVERYTHING IS IN ORDER!. Like the title says, if you only have Ubuntu (Mate) as a single OS on your PC/Laptop and you want to see the Grub menu all the time at boot time, follow the next few s…