Freezing of all screens

Try setting up another admin user account to see if the same problem continues. Please post back on whether or not this worked. Also try the Safe Mode. Please post back on whether or not this worked.

Isolating an issue by using another user account 

Safe Mode - About

If it works in the Safe Mode, try running this program when booted normally and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor.  Please use copy and paste as screen shots can be hard to read. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown. If the log won’t post, try posting it in Pastebin and provide a link in a reply        Pastebin

Etrecheck – System Information

With the exception of CleanMyMac 3, I don't see any software that normally causes problems. I suggest you increase the amount of RAM you have installed. 4 GB is on the low end for running as much software as you have open on a modern OS version. As a test, try restarting the computer, and don't open any programs except Safari. See if Safari performs more normally.

I would upgrade your RAM to at least 8 GB minimum. The 2 places I’ve seen recommended most to buy reliable RAM are below. I have purchased RAM several times, a MacBook Pro battery, and 2 hard drives from Other World Computing and have always been very satisfied with the product and service. They have on-line instructions on how to replace the RAM. OWC has also tested RAM above what Apple states is the maximum. I had 6GB installed on an early 2008 iMac supposedly limited to 4 GB and noticed an improvement.

Crucial

Other World Computing  

Most posters recommend not using cleaning programs. They can destroy normal computer operations.

CleanMyMac3 Uninstall

Check for any remaining associated files using these programs.

EasyFind – Spotlight Replacement

Find Any File

Reference Etrecheck, if the log won’t post, try posting it in Pastebin and provide a link in a reply        Pastebin

For the user password reset.

User Password Reset

User Password Reset (2)

I haven't changed the RAM in a Mac mini, so I don't really know. If you go to the web site below, they have videos that show how to upgrade the RAM. That should give you an idea of the difficulty level.

Other World Computing

You are welcome. After you post the report, go to the URL bar at the top, and copy the address of the web page. Post that in a reply.

You are welcome.

You are welcome.