Lightroom 15.0.1 has encountered problems reading this video

Thank you, @Aleke, for your response. Here is more information.

I've attached the system information file. After (another) reboot of my system, almost all of the 84 video files in the collection I was working with eventually showed thumbnails in Grid view. I still had a few videos that showed the error.  I selected one of those and went to Loupe view. It eventually showed "There was an error working with this video", and the video player buttons did not appear. I switched back and forth between Grid and Loupe view, and after a few times, the thumbnail appeared in Grid view and the player buttons appeared in Loupe view. This worked for all of the failing files. Today when I look at the collection, all thumbnails quickly appear with no errors - I assume the thumbnails are cached so Lightroom doesn't try to read the video file. 

I just looked at a folder that has 9 videos in it that I have not looked at in quite some time (i.e., the thumbnails are not cached). When I initially opened this folder today it took well over a minute to build 8 thumbnails, and one failed with the "Lightroom has encountered problems reading this video." error. [Note that some error messages end with a period and some do not... an inconsistency that I have noticed :-).] File Explorer builds all thumbnails in about one second. I navigated to another folder, then back to this folder, and Lightroom was able to build the thumbnail for the one video that failed previously. 

Lightroom is also very sluggish working with videos. It seems to me that it is much slower than it used to be. Selecting one of these videos, then going to Loupe view, it takes many seconds (I just timed one at 8 seconds) for the player buttons to become active. Then it took another 5 seconds for the video to start playing after I clicked the play button. These are not high definition files. They are AVI files that came from Mini-DV, and are 720x480 in frame size. They are all less than 5 minutes in length, many between 1 and 2 minutes. All of my files are on external SSDs, connected over USB C, so access speed should not be a significant factor.

I am also having occasions where image files (JPEG and DNG files) show error "Lightroom has encountered a problem reading this photo" [this error message doesn't have a period after it...] in Grid view. The file opens in the Develop module without error. I never saw this problem before a few months ago, but I can't say in what version of Lightroom I first noticed it. This problem seems to be much better in version 15.0.1 than previously, but is apparently not completely resolved. 

Thank you for looking into this.