Open folders in Windows Explorer mode by default (i.e. with folder pane enabled)

When you double-click a folder, it opens the folder Window without the Explorer bar enabled (default setting). When you right-click on the folder and choose Explore, it does. To set Explore as the default action, follow these steps:
  • Open My Computer window.
  • Click Tools, Folder Options, then click File Types.
  • From the list, locate the entry FOLDER with extension of (NONE).
  • Click Advanced, select Explore, then Set Default
  • Click OK and close the dialog.
To accomplish this via the Registry:
  • Open Regedit.exe and navigate to:
HKEY_CLASSES_ROOT\Folder\shell
  • In the right pane, set the value of (default) to explore