Regarding Ubuntu 16.04's "xenial" GA kernel (4.4), I've been told that the Kernel team ran into some issues with these and are now planning to release them next week. As Brandon discussed, installing the 4.15 hardware enablement (HWE) kernel - as documented at https://wiki.ubuntu.com/Kernel/LTSEnablementStack - works around this bug, too.
Regarding Ubuntu 16.04's "xenial" GA kernel (4.4), I've been told that the Kernel team ran into some issues with these and are now planning to release them next week. As Brandon discussed, installing the 4.15 hardware enablement (HWE) kernel - as documented at https:/ /wiki.ubuntu. com/Kernel/ LTSEnablementSt ack - works around this bug, too.