Windows slowly freezes, becomes unresponsible

I've been having this odd issue where watching YouTube late at night, the video will pause while the audio continues. Sometimes pressing Escape will get me out of the fullscreen video, most of the time it will not. Sometimes menus will load, sometimes they won't. Sometimes I'm able to get to the Power > Restart/Power Off options, but they will never work. Windows just slowly starts freezing and becomes utterly unresponsive, and all I can do is to force a power off. I thought a Firefox add-on might be the culprit, particularly YouTube Enhancer, but I disabled them all one by one and it's still happening. For a few months it seemed to stop - then the other day it started happening again.

Tonight I started watching a film on Netflix, where it has never crashed. For some reason the quality seemed low, despite my decent connection, so I launched the Windows app and watched it there. And lo and behold - the video paused, Windows became slow and unresponsive, and I was forced to power off yet again.

So maybe there's a link between whatever is used equally by Google and Netflix to play their content? I really haven't a clue otherwise, after a few months I'd forgotten it had ever happened until a few days ago. Yet again I am scrambling to look for a solution and coming up empty.

It's a self-build with the following specs -

Ryzen 5 3600
16GB @ 3600MHz (XMP enabled)
GigaByte B550 Aorus Elite (driver 2.13.27.501)
Radeon RX 5700 XT (driver 21.4.1)
Windows 10 Professional x64 19042.928

Does Reliability History have entries covering the problems? If so,then ---view tech details---lines 1&2 should have some information.
Also check ---dxdiag--- to see if there are any relevant entries .
Have you tried Win 10 built -in tools---Settings>troubleshoot>additional troubleshooters---?

There's nothing really showing up, though one does seem to be repeating. There were three entries for yesterday - two were for a very old, very unstable game that I play occasionally, and the third is the one that is repeated several times over the last month. You can see it here -



Nothing is showing up in DXDiag, and none of the troubleshooters found anything. When this first started happening I thought it might be the graphics card at fault, since it reminded me of an ancient issue I had with my Radeon HD 4870 many moons ago, where coming out of a fullscreen YouTube video with hardware acceleration on would cause the entire system to lock up. However, I can run the most demanding games all day on the pc and there won't be a wink of trouble out of it. Watch YouTube for a while (and now the Netflix app, apparently) and slowdown and freeze.

The ---test_wpf.exe---error supposedly can be fixed using a specific tool.
Because I do not have any personal experience with it,I can't comment further.
Suggest you carry out a search using ---test_wpf.exe ---to find the tool and make your decision accordingly.

Windows is up to date and all drivers are the latest available.

It happened yesterday while I had practically nothing open, and I wasn't watching YouTube or using the Netflix app. Now I'm wondering if it's a power supply issue - I'm hoping not as the chip shortage has really screwed with prices. The PSU (an EVGA Supernova B2 750w) is six years old and like I said, plays the most demanding games without any problems at all. I'm grasping at straws thinking it might be the culprit, to be honest.

Nothing has changed since yesterday or the date before, no driver updates or anything. Reliability History never shows anything much beyond the occasional program crashing. Yesterday the XBox Game Bar crashed (apparently, I didn't see any indication or message at the time) but that was later in the day after the pc had slowed and frozen. Event Viewer is useless because for some reason it keeps deleting old logs as soon as it boots into Windows again. So it's very hard for me to diagnose this issue.