Comment 30 for bug 1251580

The solution I used (as an idiotic layman) was to upgrade (instead of downgrading) the kernel to a version >=3.15 by using the deb files which may be found at

http://kernel.ubuntu.com/~kernel-ppa/mainline/?C=N;O=D

Pick a subdirectory with high enough version (e.g. v3.15.3-utopic/ ). You need 3 .deb's from that page: the headers-all package and the image and headers packages appropriate for your architecture (presumably x86_64 if you are using the same Optiplexs as above). Download the .deb's and install them by typing (from the directory where you downloaded them):

sudo dpkg -i linux*

Even if this version is not intended for the distribution I had, it still worked perfectly (my distribution was a "quantic" and the kernel says it goes for "utopic"). You do not need to reinstall anything. From the post mtornos made on the Ubuntu forums, I gather it worked for him too.

This update will (but again I am speaking as an idiotic layman, so maybe it won't) be automatic at some point: the kernel version keeps being updated via official updates. For example, on my other computer I am now at kernel 3.13 by just keeping to the official updates. The problem is that you might have to wait for a year or two before it reaches 3.15.x, unless you do not do it manually.