Computer starts glitching, gets worse, then eventually freezes

Not sure if this is the right place to post this issue, but I have no idea if it's a hardware, software, or other issue entirely.

It started doing this today; so far I can't nail down a pattern as to what causes it. It was turned on this morning and had been on but not used for about four hours before my wife got on. She used it for maybe 15 minutes, and then it started glitching and freezing up. The mouse became unresponsive in fits, then eventually the system froze entirely.

She rebooted and ran a full virus scan, but it came up with nothing. It also had frozen again by the time the virus scan was finished, so I had to reboot it again. I was able to use it for maybe 20 minutes or so before I experienced the same glitching and freezing. I rebooted it once more, and now I'm writing this post.

The only common denominator I can think of so far is that we were both using an internet browser when it glitched. She was able to close the browser and continue working on the document she had open for a short time before it froze entirely. When I encountered the issue, it froze too quickly for me to do anything.

Thanks for your help!

I'll give it a shot. However, that was one of the many steps that someone had me perform on a previous troubleshooting attempt, so I don't have high hopes of it working any better this time, unfortunately. That last attempt seemed to have solved my issues temporarily, but not only did they return, they returned with new issues that prompted this post. This computer is really starting to frustrate me.

"Windows Resource Protection did not find any integrity violations."

Have open the Resource Monitor and watch for spikes in usage.
To get there, press Ctrl+Alt+Del and click on Start Task Manager. Click on the performance tab. There is a button at the bottom that leads you to the Resource Monitor.
Make sure you're on the Overview/CPU tab and sort the list by descending CPU usage.
Work on the computer normally and see if any program causes a CPU spike.
Hope that helps!