Comment 30 for bug 1530405

This happened to me too about a 2 months ago:

I installed Ubuntu 16.04.
Then I installed the graphic driver (nvidia-367) about a month ago.

Everything was OK until 21 September 2016.
I think that the linux image update that I downloaded at 21 Sep (according to the update history file) totally ruined everything..

The error message in "dmesg" was:
"NMI watchdog: BUG: soft lockup - CPU#2 stuck for 23s! [nvidia-persiste ..."

It happened on startup.
But a significant delay was present *also* when shutting down.