When you open a Hypertext Markup Language (HTML) or Web archive (MHTML) file from the Open dialog box on the File menu, the file opens in the program the file was created in. For example, if you attempt to open an HTML format file in Microsoft PowerPoint that was created in Word, the file opens in Word instead. To open an HTML file in PowerPoint that was created in another Microsoft Office program, right-click the file in the Open dialog box, and then click Open With, then click Microsoft PowerPoint on the shortcut menu.
Notes
The Open With option is only available in Windows NT 4.0, Windows 2000, and Windows Millennium Edition.
For best results when you edit an HTML or Web archive file, open it in the program the file was created in.