Win 7 64 bit hard disk always active, why?

For several weeks I have noticed that the laptop does not go into sleep mode
all the time. I also noticed that the hard disk LED is blinking a lot. I checked the
system monitor and no apps are running, as for processors very little action.
The question is how does one look for the cause of the disk activity?

System
Dell Inspiron 1764 2.6 GHz intel processor 4 GB memory.
Kaspersky virus software

Go into Power Management settings, advanced settings, see if the HDD is set to never.
Been awhile since I been there, so....................