Comment 8 for bug 1239800

Are you unable to reprduce this bug if you boot back into: 3.11.0-5.11 ? If that is the case, we should be able to perform a bisect to identify the commit that introduced this.

It might also be worthwhile to test the latest mainline kernel, which can be downloaded from:
http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.12-rc5-saucy/