Thanks for your respond, Marcos.
Base on your description, and according to Task Manager and Resource monitor, during the scannings, why System (PID 4) only attempts to access the same target files? This System (PID 4) takes up over 10 or 20 seconds. The biggest target file is not over 20MB. Why it is scanned or be read for over 3.2 million bytes at every time according to the data on Resource Monitor. That means the usage of hard disk is almost 100%. Do you think this is normal?
I am so sorry for keeping asking the same question because I do worry my system may be infected or hijacked.
I just want to figure out what is going on.
1, Why operating system or any other application attempts to access the same files at every time, but not accessing other files?
2, Accessing those files for what purposes?