i'm 99% sure this is a driver crash, your graphics drivers are crashing. the black screen you see is the drivers software trying to recover the crashed drivers. if you wait about 5 minutes it usually comes back on but a restart is nearly always needed to stop it happening again during that session.
the fix, update your graphics drivers. if you are unaware as to what graphics card you have use [speccy] to find out what graphics card and model you have, go to the manufacturers website and download the latest drivers with there software.
once installed hopefully they have sorted out the crash issue with the new drivers.
also looking at some of the pics you have uploaded of speedfan with your GPU running at 104C, this a little alarming, it's reaching it's maximum operating temperature. either turn down the settings from quality to performance in the software that is associated with the GPU, eg
Intel - Intel Control Center
Nvidia - Ntune
ATI -Catalyst control center
this might help with the heat issue, or lower the graphics settings in game.
since it's a desktop, i suspect that the case is inadequate for the components, it's not providing enough airflow to the graphics card, you need to get a 'bay' cooler, you can pick them up at most PC type stores, instore or online, place one under the graphics card in the expansion slot underneath it to help with airflow.
Some older graphics drivers have issues with not turning the fans up enough on the graphics card when the temperature rises, this might also be an issue that you have, newer drivers might help lower the temperature of the card.