In addition to the subject behavior, all child windows exhibit this behavior until you close the parent window, all child windows, and start a new instance of Windows Explorer.
If the Launch folder windows in a separate process box is checked on the Tools / Folder Options / View tab, you may experience this behavior.
To workaround this issue:
1. Close all but one instance of Windows Explorer.
2. On the Tools menu, press Folder Options.
3. Select the View tab.
4. Clear the Launch folder windows in a separate process box and press Apply.
5. Press OK.