It says something about Metacity being "tainted". Metacity is the window
manager Trisquel uses by default when no 3D acceleration is available (or
when the user does not want effects). I am not sure what conclusion to draw
from that. Random crashes frequently are associated with hardware failures...
The next time this happens, try to type Ctrl+Alt+F1. If it is not a "kernel
panic", you will be presented a terminal in which you are invited to log in.
From there you can execute this command:
$ dmesg > dmesg.log
In this way, you save in your home directory the messages you took pictures
of. At the next reboot (type 'sudo reboot' and your password when it is
asked), if you can get a graphical session, you will not have troubles to
copy/paste those logs in this thread. They may help us understand the issue.
