I thought to start an isolated Firefox instance in a chroot, but it always crashes my X Server. I tried with different chroot environments (raring, trusty), and tried schroot and plain chroot too.
/proc, /sys, /dev, /dev/pts are bind-mounted into the chroot jail, as it is done automatically by schroot.
I have no idea what may cause this. When it happens, the X server restarts and I get back to the Unity login prompt, and when I log in again, Ubuntu asks me to send 3 crash reports.
The command I use to start Firefox is:
DISPLAY=:0 firefox &
DISPLAY=:0 strace -ostrace.out firefoxcreates a filestrace.out. Post these contents somewhere, maybe we find out what happens with firefox.