Looks like the same issue as LP:825777. Can you try to install the packages from https://bugs.launchpad.net/ubuntu/+source/linux/+bug/825777/comments/22 and remove fglrx, see whether you can have a successful boot?
Looks like the same issue as LP:825777. Can you try to install the packages from https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/825777/ comments/ 22 and remove fglrx, see whether you can have a successful boot?