Sometimes, when cutting, pasting, or deleting a large number of files in the "files" directory, the system may freeze. Here is the solution.
Enter the following command in the terminal:
pgrep files
This will return the PID of the "files" process.
Alternatively, you can enter the following command:
top
This will display the memory and CPU usage, and the PID of each process will be listed below.
Then, use the following command to kill the process:
kill PID