In case this might help someone, let me tell you how I solved the same problem today for a friend to whom I provide tech support. The specific issue: A .pps attachment to an e-mail. When I checked 'Default Programs' on his computer, it showed Microsoft
PowerPoint as the default program for .pps files (he has MS Office Professional fully installed, so has PP on his HD). Despite that, .pps e-mail attachments would not open.
Opened 'Default Programs' again, and clicked "Associate a file type. . ." On the list of file types, the Current Default for .pps is (hold onto your hat) Microsoft
Word. But double-clicking the .pps file type opened a window showing Microsoft PowerPoint as the "recommended program". Clicked on it. .pps listing STILL SHOWS MICROSOFT WORD AS THE CURRENT DEFAULT. Tried Browse button
and maneuvered to the Office folder containing the POWERPNT.EXE file, and clicked it. Didn't work; Current Default still listed as Microsoft Word.
Tried a third time, but this time selected "Other Programs". In that window, TWO programs appeared at the top, PowerPoint and Word. Word was highlighted, PowerPoint was not. Clicked on PowerPoint. IT WORKED!!!!!!!!!! Associated files list now showed PowerPoint
as the Current Default program. Confirmed by clicking on a .pps attachment to an e-mail and it opened.
Conclusion: Win 7's file association subroutine doesn't work properly (an understatement!). Why M$ has not fixed this horrendous bug is beyond me. I'm hoping SP2 will fix the problem, but am not holding my breath. The programmers in Redmond are TOTALLY out
of touch with the computing public.