Ubuntu 16.04 Skylake not able to shutdown and restart

I did a fresh install of Ubuntu 16.04. I am facing shutdown issues often. It hangs in a terminal with the message (sometimes shutdown works):

soft lockup, cpu#4 struck for 22s

I installed Ubuntu alongside Windows 10 with secure login turned off (as it prompted to turn off secure login to install third party drivers).

(Laptop model is Dell Inspiron 7550)

I have Dell i7559 with i7-6700HQ and GTX 960M.

After a fresh install (boot directly to the installer with nomodeset, update all packages before logging in, # dpkg-reconfigure compiz), I got this cpu lockup issue.

Then I installed Nvidia driver 364.19 from https://launchpad.net/~graphics-drivers/+archive/ubuntu/ppa and everything (shutdown, reboot and suspend) works fine now.

Hope this helps.