This looks to me another issue of https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1227202 coming out and biting. That has both a workaround and fix. Please try what is suggested on there.
This looks to me another issue of https:/ /bugs.launchpad .net/ubuntu/ +source/ linux/+ bug/1227202 coming out and biting. That has both a workaround and fix. Please try what is suggested on there.