[ubuntu] Ubuntu 16.04 - Suspend/Hibernate - will not wake up!

I have recently installed version 16.04 (was previously on 14.04). I am ruing on an HP desktop AMD64 (Athlon X2). My machine goes into what I assume to be suspend or hibeate mode if away from the keyboard for a few mins (not sure how long - maybe 10). The problem is, I am unable to wake it up. The power light is still on (which maybe means it is in suspend as opposed to hibeate). The only solution I have at the moment is to power down the machine and reboot. This is silly - I can't keep restarting my pc this way everytime I come back to it after a few mins. I have scoured the inteet looking for possible solutions and have heard that others are having some issues but maybe mainly with laptops. The one suggestion I did find was to upgrade the keel (which sounded promising). I upgraded to 4.4.8-040408-generic, however, this did not solve the problem.

What options do I have - can I somehow tu off the suspend from happening? What about a fix from Ubuntu? Any additional advice is greatly appreciated. Thank you.