Thanks, Ihor.
That change worked.


(when (eq system-type 'windows-nt)
  (setq org-file-apps
        '((\\.\\(docx\\|doc\\)\\'<file://.//(docx/|doc/)/'> . system)
          (\\.\\(xlsx\\|xls\\)\\'<file://.//(xlsx/|xls/)/'> . system)
          (\\.\\(pdf\\)\\'<file://.//(pdf/)/'> . system)
          (\\.\\(pptx\\|ppt\\)\\'<file://.//(pptx/|ppt/)/'> . system)
          (auto-mode . emacs))))