Actually my previous comment was meant for Aravisian, just trying to clear a doubt about installing .deb packages directly.
PPA means personal package archive. You added Microsoft's repository, in order to be able to install VS Code, as per the instructions on the solution that you shared. There's nothing wrong with that so no worries 
I have yet to encounter a malicious third-party PPA.
Part of my own bias is that I know exactly what goes into a person creating a PPA for debian based systems, so I retain confidence of their security due to that experience.
Software uploaded on launchpad, for example, is test-installed on a virtual machine by launchpad and must pass through Lintian.
The biggest issue with third party PPA's is not one of security against malicious software, as much as confidence against compatibility and maintenance.
Which is in itself a pretty low risk.
Hi everyone.
I just wanted to share the result.
The problem does not occur as much as before but 2 days ago while I was working with vs code then suddenly mouse click didn't work and everything was frozen.
Today something strange happens. When I was typing in Firefox the same problem happens 3 times and I was unable to click and I rebooted to get out of the mess.
Do you have any idea how I could solve this persistent problem?
@Aravisian @zenzen
Very strange issue, and is sounds like it's somehow related to the keyboard rather than a particular program like VS Code? Any chance you can use an external keyboard for a few days to see if this happens again?
When this happens, can you still open and access programs via the keyboard only i.e., using the Super key to navigate to another program and use it normally? Just trying to make sure the issue affects only the pointer.
NOTE: Wait for someone with more experience to confirm the following method or try at your own risk.
Another option that comes to mind, but I'm not entirely sure how it will affect the system is to restart the display manager. I don't know if it'll close running applications so it may lead to data loss if you haven't saved those changes. Although I know that VSCode in particular does a good job at preserving sessions even with unsaved documents.
Thanks.
I could use keyboard. I mean I press ctrl+alt+t to open terminal and I write reboot there but I could not type in firefox or other frozen programs.
I guess window key on my keyboard opens the starter menu too.
Normally when Firefox and other programs crash there's a prompt short after asking if you want to keep waiting. Did this ever show up? I'd be curious to see if the program shows up on the System Monitor or by running htop on the terminal...
You also mentioned that rebooting fixed the issue but have you tried to simply log out and log back in? In my previous comment I mentioned restarting the display manager but actually this is more like what I was referring to: Refresh Zorin OS desktop without logging out
Maybe you can try this and if it doesn't work, log out instead. But even if this does work, I must admit that I have no idea what could be causing that behavior...
My (past) experience of lockup's could be fixed simply by initiating, but not completing, a session logout. i.e. doing a Ctrl-alt-del then reversing out of the logout.
That always fixed freezing for me. I have not had the problem of late, so I can't confirm that solution still works. Also I am on Z15.3, but that should not matter.
Thanks. It worked I logout a few minutes ago from frozen desktop after that everything was fine. But it is annoying why it happens.
I tested your solution a few minutes ago.
First I should say that I saw in the task manager that firefox is working but I can't open or close it by click.
When I pressed ctrl+alt+esc mouse cursor changes but then left click did not work.
I should add another strange thing when I click on icons of Firefox, terminal, etc in the bottom panel of the desktop the click works! But I could not click anything inside firefox like close, minimize icons, etc.
Have you tested your RAM and Graphics?
I can't understand what you mean. What could I do with RAM and Graphics?
I think he means running some diagonstic tool like shown in this video (it should be the same even if it says it's for Ubuntu). I assume there must be similar tools specifically for the graphics card?
Thanks. My boot mode is UEFI and when I press esc I can't see grub menu I only see a terminal that the word Grub is written.
Is there other way to test RAM?
I think you can access the Grub menu by holding the Shift key instead. That should take you to the menu as shown in the video where you can choose the memory tester. It's possible if the logo splashscreen goes by too quickly that you have to repeat the process.
If you are still out of luck you can try this other method, by running a similar utility using the command line. I’ve tried it before with very little success since it’s a manual process, you will have to specify how much memory you want to test, so it’s a bit of a hit and miss. You can check this article for instructions to both methods (scroll to the bottom for the manual method).
On a side note: every computer uses a different key to access the boot menu, so I would recommend trying other common ones e.g.: F2, F8, F12. It's a bit of trial and error which admittedly can be annoying after having to restart a few times.
You can maybe save some time from a quick online search using the make and model of your machine followed by "boot to uefi" or "boot to bios" (bios is a term is still used interchangeably with uefi).
If booting as UEFI, then esc or tab key should work. If booting as Legacy (MBR), then holding left Shift Key should bring the grub menu up.
Ah that's good to know! I always spend a few minutes trying out different combinations until I find the right now, I'll keep this one in mind 
I rebooted my laptop many times with no success.
F2,F8,F12, Fn+F8, Fn+F12, shift and tab key does NOT work.
Pressing Esc key opens a screen like a terminal with 'Grub>' word at the beginning of each line.
Pressing Fn+F2 opens BIOS of laptop and I checked again boot mode is UEFI
My problem with frozen screen still exists I don't know what to do 
This is my grub file:
# If you change this file, run 'update-grub' afterwards to update
# /boot/grub/grub.cfg.
# For full documentation of the options in this file, see:
# info -f grub -n 'Simple configuration'
GRUB_DEFAULT=5
GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""
# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"
# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console
# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480
# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true
# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"
# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"
GRUB_THEME=/usr/share/grub/themes/zorin/theme.txt
It is strange that I can't see the grub menu I have seen that menu before with other distros of linux many times. Why I can't see that? Should I customize something?
I updated one line of my grub file to
GRUB_TIMEOUT_STYLE=menu
and after I could only see a menu with 3 options. 1. Zorin 2. Advanced zorin 3. UEFI firmware settings
I commented that line
GRUB_TIMEOUT_STYLE=hidden
Now after pressing tab key I could see that menu with 3 options.
Yes, you addressed that rightly. You also might consider changing the Grub Timeout to "10" instead of "5".
The system is freezing on apps other than VS Code, correct?
Yes it freezes on Firefox too. Right now I wanted to answer your question and it freezes, only terminal and Firefox has been opened.
I changed grub Timeout to 10 and I commented this line GRUB_TIMEOUT_STYLE=hidden or put it there, or make it equal to menu but I can't see the grub menu I just see that menu I mentioned in my previous comment here.
I'm wondering if using a live USB would give you access to the memtest option. I'm seem to remember that option was available when you plug in the USB with the .iso image to test a distribution without installing it 