Hi everyone,
I seem to have the exact same problem that Phil here is facing ever since i updated to 16.04.
(Note: I did a fresh install of 16.04 over 15.10, not the upgrade from within 15.10). But there is a slight difference. If I try to graphically shutdown my laptop (the top panel button I mean) , it acts in a similar way to how Phil’s laptop does & I end up holding the power button to shut it down.
But if I type the command poweroff in the terminal , it seems to shutdown normally. I have been using the poweroff command ever since. And I am updating my system regularly. I will try some of the solutions posted here.
On the ubuntu forums there us a similar thread, one of the recommendations is to unquiet grub. This gives a running commentary on the boot and shut down process. As I also have a random long shutdown on mate16.04, I’ve done this. The other day I had a long shutdown and the commentary ended at this point.
“Stopped Rise network interfaces” with a flashing cursor underneath it. When the text started scrolling again, it was too fast to read what followed, but it was only a page or so before it shut down.
I hope this helps somebody to work out what’s going on.