I've marked this as a duplicate of Bug #566379 [1] because the symptoms and fix are exactly the same (however, this bug breaks because of an -intel upgrade, whereas the other breaks because of a kernel upgrade). If you believe this is a separate bug, please feel free to remove the duplicate status.
To deal with the bugs experienced after re-enabling KMS, please file a new bug against -intel mentioning that you have re-enabled KMS.
I've marked this as a duplicate of Bug #566379 [1] because the symptoms and fix are exactly the same (however, this bug breaks because of an -intel upgrade, whereas the other breaks because of a kernel upgrade). If you believe this is a separate bug, please feel free to remove the duplicate status.
To deal with the bugs experienced after re-enabling KMS, please file a new bug against -intel mentioning that you have re-enabled KMS.
[1] https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/566379