Unable to open .PPS attachments directly from Windows Mail in Windows Vista

Cause :This happens if the Open command is missing for .PPS and/or .PPT file types.
Resolution:

For .PPS files (Microsoft PowerPoint Slideshow)

* Click Start, type regedit.exe and press ENTER
* Navigate to the following branch:
* HKEY_CLASSES_ROOT\PowerPointViewer.SlideShow.11\shell\Show
* Right-click Show and click Rename
* Type the word Open so that Show is replaced by Open command
* If you have PowerPoint Viewer 2007 installed, repeat the above steps in this key, as well:

HKEY_CLASSES_ROOT\PowerPointViewer.SlideShow.12\shell\Show

* After changing Show to Open, close Registry Editor window.