I can completely reproduce the bug when xserver-xorg-input-synaptics is uninstalled.
I don't know if this is a duplicate of bug #632791 but indeed, using firefox or iceweasel crashes the X server in the exact same way. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org