[ubuntu] System won't wake up after sleep

Hello,

I've been experiencing this issue since I've installed the version 16.04 LTS (fresh install, updated today), basically the system won't boot up after it has been put to sleep (black screen, laptop lights on).

What can I do to help me understand what is causing this?

@ My Current Specs:
- HP ZBook 14 2015
- Intel Core i5 5200U
- Intel HD Graphics 5500
- SSD Drive
- 64 bits OS

Thanks.