PC stops working and can't switch off

[DrWambua]

Hello there. I have this HP SFF desktop DC series (not sure which one) running on Windows 10 perfectly until recently when I noticed somthing unusual. When playing media files, it just had the screen display BLACK, monitor went to sleep, and some weird sounds coming from the computer. The funny part is, I couldn't switch off the computer even by long pressing the power button for more than a minute. What's the problem please?

 

[webworkings]

Does this actually only happen when running specific types of media files? And in what software is it being run? Do you get any problems at all running other media and/or other software for media? Does it happen ever when doing anything else?