PC Shutting down

having just recently ordered a PC through PC specialist I can say I'm really happy with the setup there's been no issues with performance while gaming or simply navigating my desktop, however, I have had two instances recently where I have gone to shut it down but the PC itself remains on for more than a few few minutes, the fans remain in motion and it's like the PC itself has not shut off but my keyboard or mouse do not respond and my monitors are registering as if there is nothing to display, thus forcing me to force a shut down directly by holding the power button down.

I'm reluctant to keep doing this obviously and it's only happened twice over the last few days, nothing springs to mind as to why it would be doing this, only thing that does somewhat come to mind is I am now running wallpaper engine? though I had that on my last PC and this issue never happened then, there's been no anomalies with my temps that I can see before shutdown, specs are as follows: