I used PowerPointViewer to read .ppt, .pps files in email. It works fine in one user-A, but does not work in another user-B in the same computer. This is because .pps is associated to wrong programs in user-B. PowerPointViewer does not show up as a program in "control panel / defaut program", so I can't correct this problem. There is a great article from mydigitallife which I thought can solve my problem: http://www.mydigitallife.net/2008/0...file-extension-associations-in-windows-vista/ But I can't make it to work: For both users, Assoc & ftype looks the same Assoc .pps .pps=PowerPointViewer.SlideShow.11 ftype PowerPointViewer.SlideShow.11 PowerPointViewer.Slideshow.11=C:\Program Files <x86>\Microsoft Office\Office12\pptview.exe “%1” After I remove assoc and ftype for .pps (in user-B space) per article, by doing assoc .pps=(blank) ftype .PowerPointViewer.Slideshow.11=(blank) "Control panel / default program" still shows the wrong programs associated to .pps; I expect to see no association. Any help will be greatly appreciated.