I am on Ubuntu 14.04 on this hardware (with no external/proprietary driver needed).
These are the enabled official repositories (all but proposed) and these are the external ones (Google Chrome, Dropbox, Google Talk Plugin).
The problem is that, if (and only if) I wait for GRUB to finish its countdown, then when I come to Lightdm the system freezes.
I can move the mouse but there is noy input on click, more important there is not keyboard input, (so no Ctrl+Alt+F1-7 to investigate and to shutdown, nor SysRq+REISUB, only force shutdown with long press power button).
If at boot I skip the GRUB waiting time (just press Enter), the problem does not appear and everything works great.
Any hint on what might be causing it and how to investigate?