find: ‘/home/marcos/.cache/doc’: Permission denied
find: ‘/home/marcos/.cache/dconf’: Permission denied
3150807 1849588 -rw-rw-r-- 1 marcos marcos 1893974016 Aug 29 17:21 /home/marcos/Downloads/linuxmint-19-xfce-64bit-v2(1).iso
7868522 0 -rw-r--r-- 1 marcos marcos 0 Aug 29 12:57 /home/marcos/ISO/linuxmint-19-xfce-64bit-v2.iso
find: ‘/home/marcos/.gvfs’: Permission denied

Good, you have a copy in your Downloads folder.

Let's check if you have an folder in your home directory called ISO:

Note that ~ is a short-hand way on the command line of referring to your home directory (in your case /home/marcos). "Folder" and "directory" are interchangeable terms.

total 265996
-rw-r--r-- 1 marcos marcos 2159 Jun 5 12:14 {972ce4c6-7e08-4474-a285-3208198ce6fd}.xpi
-rw-r--r-- 1 marcos marcos 2603859 Jun 5 12:14 activity-stream@mozilla.org.xpi
-rw-r--r-- 1 marcos marcos 695 Jun 5 11:51 application.ini
-rw-r--r-- 1 marcos marcos 8671 Jun 5 12:14 aushelper@mozilla.org.xpi
-rw-r--r-- 1 marcos marcos 124823 Jun 5 11:23 blocklist.xml
-rw-r--r-- 1 marcos marcos 245 Jun 5 12:14 channel-prefs.js
-rw-r--r-- 1 marcos marcos 0 Jun 5 11:47 chrome.manifest
-rwxr-xr-x 1 marcos marcos 254496 Jun 5 12:14 crashreporter
-rw-r--r-- 1 marcos marcos 4003 Jun 5 11:25 crashreporter.ini
-rw-r--r-- 1 marcos marcos 787 Jun 5 11:24 crashreporter-override.ini
-rw-r--r-- 1 marcos marcos 12667 Jun 5 11:23 default128.png
-rw-r--r-- 1 marcos marcos 798 Jun 5 11:23 default16.png
-rw-r--r-- 1 marcos marcos 2145 Jun 5 11:23 default32.png
-rw-r--r-- 1 marcos marcos 3607 Jun 5 11:23 default48.png
-rw-r--r-- 1 marcos marcos 5168 Jun 5 11:23 default64.png
-rw-r--r-- 1 marcos marcos 157 Jun 5 12:14 dependentlibs.list
drwxr-xr-x 3 marcos marcos 4096 Aug 26 08:00 Desktop
drwxr-xr-x 5 marcos marcos 4096 Aug 30 11:59 Documents
drwxrwxrwx 8 marcos marcos 20480 Aug 30 13:25 Downloads
drwx------ 6 marcos marcos 4096 Jun 21 10:57 Dropbox
-rw-r--r-- 1 marcos marcos 1227260 Jun 5 11:23 EmojiOneMozilla.ttf
-rw-r--r-- 1 marcos marcos 3074 Jun 5 11:24 en-US.aff
-rw-r--r-- 1 marcos marcos 578759 Jun 5 11:24 en-US.dic
drwxr-xr-x 2 marcos marcos 4096 Feb 16 2017 e-Sword
-rwxr-xr-x 1 marcos marcos 191560 Jun 5 12:14 firefox
-r-------- 1 marcos marcos 153354240 Jan 11 2018 firefox-57.0.4.tar-1
-rwxr-xr-x 1 marcos marcos 191656 Jun 5 12:14 firefox-bin
-rw-r--r-- 1 marcos marcos 1449 Jun 5 12:19 firefox-bin.sig
-rw-r--r-- 1 marcos marcos 864581 Jun 5 12:14 firefox@getpocket.com.xpi
-rw-r--r-- 1 marcos marcos 1449 Jun 5 12:19 firefox.sig
-rw-r--r-- 1 marcos marcos 19037 Jun 5 12:14 followonsearch@mozilla.com.xpi
-rw-r--r-- 1 marcos marcos 464592 Jun 5 12:14 formautofill@mozilla.org.xpi
-rw-r--r-- 1 marcos marcos 88017 Feb 17 2017 hs_err_pid5791.log
drwxrwxr-x 2 marcos marcos 4096 Aug 30 13:26 ISO
-rwxr-xr-x 1 marcos marcos 105152 Jun 5 12:14 libclearkey.so
-rw-r--r-- 1 marcos marcos 1449 Jun 5 12:19 libclearkey.so.sig
-rw-r--r-- 1 marcos marcos 899 Jun 5 12:14 libfreeblpriv3.chk
-rwxr-xr-x 1 marcos marcos 567840 Jun 5 12:14 libfreeblpriv3.so
-rwxr-xr-x 1 marcos marcos 59880 Jun 5 12:14 liblgpllibs.so
-rwxr-xr-x 1 marcos marcos 1675568 Jun 5 12:14 libmozavcodec.so
-rwxr-xr-x 1 marcos marcos 208648 Jun 5 12:14 libmozavutil.so
-rwxr-xr-x 1 marcos marcos 6072 Jun 5 12:14 libmozgtk.so
-rwxr-xr-x 1 marcos marcos 93128 Jun 5 12:14 libmozsandbox.so
-rwxr-xr-x 1 marcos marcos 1021640 Jun 5 12:14 libmozsqlite3.so
-rwxr-xr-x 1 marcos marcos 257152 Jun 5 12:14 libnspr4.so
-rwxr-xr-x 1 marcos marcos 697336 Jun 5 12:14 libnss3.so
-rwxr-xr-x 1 marcos marcos 466904 Jun 5 12:14 libnssckbi.so
-rw-r--r-- 1 marcos marcos 899 Jun 5 12:14 libnssdbm3.chk
-rwxr-xr-x 1 marcos marcos 158824 Jun 5 12:14 libnssdbm3.so
-rwxr-xr-x 1 marcos marcos 196344 Jun 5 12:14 libnssutil3.so
-rwxr-xr-x 1 marcos marcos 18800 Jun 5 12:14 libplc4.so
-rwxr-xr-x 1 marcos marcos 18672 Jun 5 12:14 libplds4.so
drwxr-xr-x 4 marcos marcos 4096 Jan 27 2017 LibreOffice_5.3.0.3_Linux_x86-64_deb
-rwxr-xr-x 1 marcos marcos 176952 Jun 5 12:14 libsmime3.so
-rw-r--r-- 1 marcos marcos 899 Jun 5 12:14 libsoftokn3.chk
-rwxr-xr-x 1 marcos marcos 266448 Jun 5 12:14 libsoftokn3.so
-rwxr-xr-x 1 marcos marcos 328600 Jun 5 12:14 libssl3.so
-rwxr-xr-x 1 marcos marcos 85443616 Jun 5 12:14 libxul.so
-rw-r--r-- 1 marcos marcos 1449 Jun 5 12:19 libxul.so.sig
-rw-r--r-- 1 marcos marcos 223 Jun 5 12:14 manifest.json
drwxr-xr-x 192 marcos marcos 12288 Aug 30 09:06 MEGA
-rwxr-xr-x 1 marcos marcos 860784 Jun 5 12:14 minidump-analyzer
drwxr-xr-x 10 marcos marcos 4096 Aug 24 07:21 Music
-rw-r--r-- 1 marcos marcos 1829 Dec 10 2017 'New Database'
-rw-r--r-- 1 marcos marcos 17121434 Jun 5 12:14 omni.ja
-rw-r--r-- 1 marcos marcos 566768 Jun 5 12:14 onboarding@mozilla.org.xpi
drwxr-xr-x 3 marcos marcos 4096 Aug 28 21:25 Pictures
-rwxr-xr-x 1 marcos marcos 281800 Jun 5 12:14 pingsender
-rw-r--r-- 1 marcos marcos 166 Jun 5 12:14 platform.ini
-rwxr-xr-x 1 marcos marcos 187304 Jun 5 12:14 plugin-container
-rw-r--r-- 1 marcos marcos 1449 Jun 5 12:19 plugin-container.sig
-rw-r--r-- 1 marcos marcos 2472 Jun 5 12:19 precomplete
drwxr-xr-x 2 marcos marcos 4096 Feb 16 2017 Public
-rw-r--r-- 1 marcos marcos 0 Jun 5 11:48 removed-files
-rw-r--r-- 1 marcos marcos 1064151 Jun 5 12:14 screenshots@mozilla.org.xpi
drwxr-xr-x 2 marcos marcos 4096 Feb 16 2017 Templates
-rw-r--r-- 1 marcos marcos 825 Jun 5 11:24 Throbber-small.gif
-rwxr-xr-x 1 marcos marcos 256592 Jun 5 12:14 updater
-rw-r--r-- 1 marcos marcos 681 Jun 5 12:14 updater.ini
-rw-r--r-- 1 marcos marcos 2153 Jun 5 11:24 updater.png
-rw-r--r-- 1 marcos marcos 132 Jun 5 12:14 update-settings.ini
drwxrwxr-x 3 marcos marcos 4096 Aug 24 12:34 Upgrade-Backup
drwxr-xr-x 3 marcos marcos 4096 Mar 3 09:02 Videos
-rw-r--r-- 1 marcos marcos 9783 Jun 5 12:14 webcompat@mozilla.org.xpi

Wow, you shouldn't have most of these files in that directory. It would indicate an incorrect package install at some point.

Also, I erred in asking you to list the home directory to see if it contained ISO since the output from your find command showed that it existed - my bad. I'll have to use the late hour as my excuse (the bells have just run midnight here).

Right, let's change directory to ~/ISO:

Then copy that iso over:

Then we'll delete the zero size one that is already there:

Then you can carry on with the rest of the verification process as listed on the Mint page.

Hey, you better get to bed! It is only 5:00pm here.
After I put in the second code the output is:

cp ~/Downloads/linuxmint-19-xfce-64bit-v2(1).iso ./
bash: syntax error near unexpected token `('

Oh damn, this is so difficult doing all this at a distance. I would have just used tab completion normally. If there are any misinterpreted characters (or spaces etc.) in a command line filepath/name then enclose the filepath/name in quotes, e.g.:

On a general note, I have to admit that I don't think I am going to have the time at all to walk you through the whole installation process, Mark. Also, and don't take this personally, but perhaps you are not quite ready yet to do so. Maybe what you need is to take a while to get used to Linux and its quirks. You have a working system, albeit a bit of a Frankenstein one with three desktop environments, but it should be workable. Once you feel you're ready, you can get round to installing a single desktop environment flavour of Mint.

Alternatively perhaps someone who has more time than I do can step up to the plate.

That is fine, hydruga. I understand. I admire your patience with me. I will see what I can do from here.

I wish I could invite you over for a coffee and some good bars my daughter bakes. But you are too far away.
Thank you for all your time.
Mark

That sounds delicious (even though I don't know what a "bar" is ).

Let me know how the iso verification goes though - I'm not quite off to bed yet.

Bars are a kind of cake.
I ran the code and it took a while then it didn't bring back any output.
This machine is crazy or just maybe it is the man running it.
Hey, why don't you come over and we can go birding. I love birds and know more about them then Linux. Wouldn't have to know much about to know more than I know about Linux!
Good night,
Mark

An interesting hobby to have. Lots of fresh air!

That is indeed strange. You need to paste the commands and output here so that I or somebody else can try and figure out what's going wrong. Otherwise it's difficult to say what happened.

Hydrurga, you wouldn't believe what I did last night. I decided to erase my USB memory and start all over. And following your earlier instructions and the guide you recommended I installed a clean copy of Linux Mint xfce.I cleaned off my hard drive. I was up till after midnight! Last night it worked great. Now this morning it has been locking up at times and having trouble rebooting. Probably like you suggested my problem is with the computer. I will see how it continues and maybe take it to a shop. Right now it is working fine again.
I am not asking you to do anything. I know I have exhausted your great patience.
Oh, one little question,
Is it okay that in the Driver Manager it says,
No propriety drivers in use?
Thank you again for all your help. Without what you helped me with I would not have been able to do it.
Mark

That's great news (but not so good news about the lockups). Well done on installing it! I was obviously wrong in suggesting you wait a while.

I've never used Nvidia, but as far as I'm aware you have the choice between the Nvidia proprietary driver or the open source Nouveau one. If you're getting lockups still, then maybe you should try the Nvidia driver - you should be able to select it through the Driver Manager. Anyway, run both options for a while each and see if you notice any differences.

Perhaps the issue has nothing to do with the graphics driver, but it will be worth trying as much as you can to resolve it.

Thanks. The problem is that no driver shows up in the Driver Manager.

Can you please post the output from inxi -Fz?