I recently installed 16.04 on a pen drive and it keeps on coming up with a running in low graphics mode pop up and wont let me do anything. I'm not the greatest with terminal. help would be appreciated.
EDIT: I also cannot get to grub menu when I hold shift during boot it takes me to what looks like a terminal. Also don't believe I have a user name or password.
I faced the same infamous "Low graphics mode" issue after upgrading to 16.04 out of my curiosity from 14.* LTS. I tried installing/uninstalling graphics drivers (open source/official), configuring/reconfiguring various desktop managers, trying various previous kernels, installing/reinstalling GL/mesa drivers via apt-get, removing ~/.*authority, creating xorg.conf, changing/fixing/blacklisting graphics kernel modules and so on, but nothing worked
Finally, I saw that /etc/lightdm/lightdm.conf didn't have any greeter-session at all. So, added greeter-session=unity-greeter and then got the lightdm login page instead of flickering black screen saying "System program problem..." dialog box appearing and
disappearing every few seconds.
Then, I got into another infamous issue - login loop. For this, I switched the desktop environment to GNOME metacity as none of the other worked - Ubuntu, Unity8 Mir, Gnome Compiz, etc. Finally, I was able to login, but "system settings" was having issues - unity-control-center and gnome-control-center were crashing with SegFault.
So, I installed the latest built mesa driver from mesa-12.* sources (only half built as there was some llvm error but installed the so far stuff anyway which included the intel drivers as I saw), and at last "system settings" opened successfully.
nomodesetto the end of the options, and then boot into "Try Ubuntu" as usual. Does that help? – May 02 '16 at 03:48