To determine which applications in Windows 7 are responsible for activity on your hard disk, including which files and folders are being accessed you can use either Process Explorer or Resource Monitor. Although, Windows 7 offers an enhanced version of the Resource Monitor tool, Process Explorer is not part of the native operating system and you need to download it from Microsoft’s TechNet. Process Explorer allows you to determine information related to running programs such as, which program has a particular file or directory open or handles opened and DLLs loaded.
After you download the utility and expand the compressed file to a meaningful location such as, c:\processexplorer, you can start the tool by typing c:\processexplorer\procexp.exe in the Start search text box and pressing the enter key.
The unique capabilities of Process Explorer make it useful for tracking down DLL-version problems or handle leaks, and provide insight into the way Windows and applications work. In handle mode, you can see the handles that the process selected in the top window has opened. The Process Explorer search capability discovers which processes have particular handles opened or DLLs loaded.
Note, that if you become a big fan of Process Explorer, you can set it as the default tool instead of Windows 7 Task Manager. On the Options menu, choose to have Process Explorer open instead of Task Manager whenever Task Manager is started, or you can ensure that the Process Explorer windows is always on top and always visible.
Download Process Explorer here.