Whenever I start my computer, Scandisk starts running even I proper shut down the PC last time.

Do as following:

A. Open regedit and goto:

Code:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager

In right-side pane, change the value of BootExecute to:

autocheck autochk *

B. If the above trick doesnt help then give following commands in Command Prompt:

chkntfs /x drive_name

for e.g., if ScanDisk runs automatically for C: and D: drives, then give following commands one by one:

chkntfs /x C:
chkntfs /x D: