Same problem here.
Problem surfaced moving from 3.16.0-50-generic to 3.16.0-51-generic
Linux soup-HP-ProBook-4530s-SSD 3.16.0-50-generic #67~14.04.1-Ubuntu SMP Fri Oct 2 22:07:51 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
Same problem here.
Problem surfaced moving from 3.16.0-50-generic to 3.16.0-51-generic
Linux soup-HP- ProBook- 4530s-SSD 3.16.0-50-generic #67~14.04.1-Ubuntu SMP Fri Oct 2 22:07:51 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux