Programs failing, graphics failing, but not GPU?

you really should fill up the rest of your specs and what windows you are using.

that sounds like your computer was trying to free up RAM space but not quick enough. there might be a program in your PC that is a memory hog. or could be the game itself. you may need to upgrade your RAM or remove that program. you can try searching in the Event Viewer if your OS attempted to clear memory resources right before your forced your PC to shutdown. it usually shows up as a warning and indicating what exe file it tried to stop.

it may be caused by your page file/virtual memory. you can try to turn it off or reset the virtual memory on your C drive. you can refer to the link below as a guide if you are unfamiliar with it.
https://www.online-tech-tips.com/computer-tips/simple-ways-to-increase-your-computers-performace-configuring-the-paging-file/

you can also try to check the health of your HDD/SSD. either you can run "chkdsk /scan /x c:" in command prompt. or download the CrystalDiskInfo.

i've been having some strange issues with my computer like you describe - mine would start to run sluggish, extremely sluggish. I had tried everything i could think of, scanned for malware etc, cloned a backup disk back to the OS drive - the "magic" trick of removing all ram but the one stick in the A1 slot would correct the sluggishness - the sluggishness was so bad that i'd open "my computer" and it would take 5 seconds and then only open to a white box with no drive icons showing. I would shut the computer down, reboot, and 3 times it would actually be worse on the reboot. Then i started having black screens - i might hit a link on a website and screen would just go black, or it would return from sleep mode to a black screen, or sometimes go black while idle. But even though the "magic" one stick of ram trick would work, the issues would return in a few days.

I identified the issue being my GPU (GTX 1070) after moving my GPU to another computer and the issue followed it to the 2nd computer. After doing some research ( https://wccftech.com/nvidia-gtx-1070-memory-issue/ ), i stumbled on a few threads where Nvidia apparently shipped a good numbrer of GTX 1070 boards with Micron VRam chips vs Samsung chips because of shortages, and the micron chips are causing some issues. If you download & run GPU-Z you can identify which chip your gpu has. Most of the GTX 1070 3rd party vendors (Evga, MSI etc) have released updated VBios for their 1070 GPUs with Micron chips. I had to contact Zotac support asking if / when they were going to release an updated VBios and they emailed me a link (nothing on their website about it)

I've updated it, and still had the same issue, in this case, strange "Black screens" when i'd clik on a webpage link, or trying to return the computer from sleep mode. Once it goes into black screen, the only thing you can do is a hard reset / reboot. Other symptoms have been artifacts on the screen, stuttering or flickering image, to name a few.

After the latest black screen incident, I ran Whocrashedit and found it identified it was the Nvidia driver and gave a link to search. I found a number of posts about Nvidia's driver being buggy and which driver to roll back to. Here's a link that might help https://forums.geforce.com/default/topic/1035287/nvlddmkm-sys-crashing/?offset=1

hope that helps