I have a PC with both OS installed (Ubuntu 16.04 & Windows 10) on an SSD (Samsung, 500Gb)
Since the moment I installed Ubuntu and my PC boots with GRUB, every time I want to turn it back on I have to unplug the power cord for 30s or else it wont start.
Also, when I'm on Windows and the PC hibernates I can't turn it back on, I have to unplug, wait, and turn it on (And the power led keeps twinkling for a while after unpluging the cord).
The computer is brand new, and its unlikely this being due to a hardware issue.
Let me know if there is more relevant info I can provide.