I recently upgraded from Ubuntu 11.10 to 12.04. If it makes any difference, my system is a Dell Inspiron 1520. I encounter a problem whenever I shutdown or restart; it kills all running processes...
askubuntu.com
have you spent some time working through this?
Which OS do you currently have installed?.....install one OS and stay with it....Linux Mint 21.3 will be the better one.
The problem does not lay with the OS....it is your pc
I still think the link above holds the answer....because there was a known problem with a Dell 1520. There are a few links on that same page that are worth following.