There was indeed a regression between 3.13.0-26 and 3.13.0-27. And between 3.13.0-28 and 3.13.0-29 if you've installed AceLan's 3.13.0-28 kernel.
By the way, the bug hasn't been fixed yet in the official kernel, but it's been taken care of. See https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1305522
There was indeed a regression between 3.13.0-26 and 3.13.0-27. And between 3.13.0-28 and 3.13.0-29 if you've installed AceLan's 3.13.0-28 kernel.
By the way, the bug hasn't been fixed yet in the official kernel, but it's been taken care of. See https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/1305522