I'm also having this issue regularly, at least two times a day. I can't say for sure but it seems that opening/closing tabs in Chrome is what triggers a crash most frequently here.
$ apt-cache policy xserver-xorg-core xserver-xorg-core: Installed: 2:1.17.2-1ubuntu9 Candidate: 2:1.17.2-1ubuntu9 Version table: *** 2:1.17.2-1ubuntu9 0 500 http://archive.ubuntu.com/ubuntu/ wily/main amd64 Packages 100 /var/lib/dpkg/status -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to x11proto-core in Ubuntu. https://bugs.launchpad.net/bugs/1484380 Title: Xorg regular crash on wily To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/x11proto-core/+bug/1484380/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp