Sometime my hard-disk stop and start same time

what is the problem in my hard-disk sometime it's stop and start same time .

I don't know how you could "see" if a hard drive is "stopping" and "stopping". That makes me think the platter motor stops spinning and then starts again. And the R/W head is controlled by a "stepper" motor that works by moving (stepping) to new locations, stopping, then stepping to the next location.

So exactly what symptoms are you noticing?

As Roland notes, there are many programs and services that might access the drive, including security scanners, Windows Update, and Windows Indexing. These are all normal activities.