Live iso vs. i386

[Lou Poppler <LouPoppler@cableone.net>]

I want my i686 netbook to be ready for testing the next release.
I experimented with booting debian-live-10.6.0-i386-kde+nonfree.iso
but it fails sometimes, but not always, in a way I don't understand.

After I select the live system from the Main Menu, it stays on the menu display
for a few minutes, then it grinds awhile on a black screen which acquires a
couple log messages, then switches to a metallic blue background with 

                  âû  âû  âû  

displayed in the center.  After a minute or two, that disappears and any VT I
switch to contains a scrolling log, alternating these 2 lines forever:

[(timestamp)] SQUASHFS error: Unable to read fragment cache entry [3e0bc32a]
[(timestamp)] SQUASHFS error: Unable to read page, block 3e0bc32a, size 6784

with very infrequent addition of 3 or 4 repeats of these 2 lines:

[(timestamp)] SQUASHFS error: Unable to read data cache entry [34454365]
[(timestamp)] SQUASHFS error: Unable to read page, block 34454365, size b294

The numbers are always the same, any time the machine goes to this dead end.

I would welcome any advice for how I can troubleshoot or fix or workaround this.

Here are some easy things I have done to rule out obvious problems:
lwp@william:~$ wget https://cdimage.debian.org/images/unofficial/non-free/images-including-firmware/archive/10.6.0-live+nonfree/i386/iso-hybrid/MD5SUMS
lwp@william:~$   grep kde+nonfree.iso  MD5SUMS
7039fe4a813446a8207dd08ab0906b11  debian-live-10.6.0-i386-kde+nonfree.iso

lwp@william:~$   ls -al /usr/local/share/linux-torrents/debian-live-10.6.0-i386-kde+nonfree.iso
-rw-r--r-- 1 lwp staff 3409182720 Oct 13 10:54 /usr/local/share/linux-torrents/debian-live-10.6.0-i386-kde+nonfree.iso
lwp@william:~$   md5sum /usr/local/share/linux-torrents/debian-live-10.6.0-i386-kde+nonfree.iso
7039fe4a813446a8207dd08ab0906b11  /usr/local/share/linux-torrents/debian-live-10.6.0-i386-kde+nonfree.iso

root@william:/home/lwp#    cp /usr/local/share/linux-torrents/debian-live-10.6.0-i386-kde+nonfree.iso /dev/sdb; sync
root@william:/home/lwp#    dd if=/dev/sdb bs=512 count=6658560 | md5sum
6658560+0 records in
6658560+0 records out
7039fe4a813446a8207dd08ab0906b11  -
3409182720 bytes (3.4 GB, 3.2 GiB) copied, 120.712 s, 28.2 MB/s
(repeated dd|md5sum  10 times, same result)

(Moved USB stick to target 686 netbook, verified 10 times there:)
root@netbook:~# dd if=/dev/sdc bs=512 count=6658560 | md5sum
7039fe4a813446a8207dd08ab0906b11  -
6658560+0 records in
6658560+0 records out
3409182720 bytes (3.4 GB, 3.2 GiB) copied, 157.636 s, 21.6 MB/s

(Ran memtest86+  3 passes on netbook with no errors.)