Intermittently frozen screen

My screen freezes for a few seconds to a few minutes up to a few times per minute but the system is not frozen. Spotify will continue to play, VLC sound will continue to play, Youtube sound in Firefox or Chrome will continue. It appears that mouse clicks or Page Up/Down keyboard commands will stack up and execute as soon as the screen starts moving again. Mute keyboard command will not execute until the screen starts moving again.

If I log out and log back in or reboot, the freezes will go away for a while but they eventually come back and get worse until I have to log out again.

I have tried System Monitor and TOP but I don't see any obvious causes. Error logs don't show anything obvious to an idiot (me - but I really am an idiot here). I don't know how to troubleshoot this any further.

This problem has been occurring for more than a year but different versions of Ubuntu are better or worse. 21.04 was very good (I could live with it) but 21.10 is really bad (I can't live with it). I don't remember what version of Ubuntu started it (2019?). Same PC since 2017. Same functional configuration HTPC since 2010.

Other freezes searched do not seem to be the same problem. Their solutions did not help.

Dual boot to Win10 with no issues there.

• CPU - AMD A8-7600 w Radeon R7
• MOBO - ASROCK fm2a88m pro 3+
• RAM - 2 x 8 GB
• SSD partition - 270 GB - 130 GB free

What can I do to troubleshoot this further?

edit 2021/01/04: Yesterday while I was writing this post, screen freezes where constantly interrupting me. Today when I ran the below commands, screen freezes were nearly nonexistent. Some days have always been better than others. I did perform an Update/Upgrade and a reboot this morning but I do not think my problem has resolved until I experience a longer period without screen freezes.

I will also try a live USB suggested below when I get the chance.

ed@ed-htpc:~$ sudo dmidecode -s bios-version
P2.60
ed@ed-htpc:~$ free -h 
               total        used        free      shared  buff/cache   available
Mem:            13Gi       3.1Gi       1.6Gi        97Mi       8.9Gi        10Gi
Swap:          2.0Gi       1.0Mi       2.0Gi
ed@ed-htpc:~$ sysctl vm.swappiness
vm.swappiness = 60
ed@ed-htpc:~$ swapon -s
Filename                Type        Size    Used    Priority
/swapfile                               file        2097148 1792    -2

Also, this HTPC records television from a network attached TV tuner (MythTV <-> HDHomerun) and the recorded video file shows no interruptions if the screen freezes during a background recording. MythTV will also continue to play sound while the screen is frozen during video playback.

edit 2021/01/07: Increasing swap to 4 GB did not fix problem

ed@ed-htpc:~$ free -h
               total        used        free      shared  buff/cache   available
Mem:            13Gi       4.4Gi       620Mi       166Mi       8.6Gi       8.7Gi
Swap:          4.0Gi       244Mi       3.8Gi

edit 2021/01/12: Tests run so far seem to rule out hardware problems. I do not know how to troubleshoot this further. I have looked in the Logs app but I do not know how to recognize a significant message. I should wait until the freezes become a major disruption and then look at some kind of log but I don't know what. (or look at logs for 2021/01/03 - that day was very heavy)

BIOS

ASROCK FM2A88M Pro3+

Your BIOS is the most current, at 2.60.

SWAP

Let's increase your /swapfile from 2G to 4G and see if that solves the problem.

Note: Incorrect use of the rm and dd commands can cause data loss. Suggest copy/paste.

In the terminal...

sudo swapoff -a           # turn off swap
sudo rm -i /swapfile      # remove old /swapfile

sudo dd if=/dev/zero of=/swapfile bs=1M count=4096

sudo chmod 600 /swapfile  # set proper file protections
sudo mkswap /swapfile     # init /swapfile
sudo swapon /swapfile     # turn on swap
free -h                   # confirm 16G RAM and 4G swap

Edit /etc/fstab, using sudo -H gedit /etc/fstab or sudo pico /etc/fstab.

Confirm this /swapfile line in /etc/fstab... and confirm no other “swap” lines... use SPACES in this line... confirm NO TABS...

/swapfile  none  swap  sw  0  0

reboot                    # reboot and verify operation

MEMTEST

Go to https://www.memtest86.com/ and download/run their free memtest to test your memory. Get at least one complete pass of all the 4/4 tests to confirm good memory. This may take a few hours to complete.