>>>>I ran your program and it returns the correct association. Computer magic ?
>>>>But I still get a "No association." error.
>>>
>>>When you right click on the .PPT file, what action verb is on the top of the shortcut menu? Try to run with default action
>>>

>>>*lnResult=ShellExecute(FindWindow( 0, _SCREEN.caption), "Open", tcDocument, "", "c:\temp\", 1)
>>>lnResult=ShellExecute(0, "", tcDocument, "", "", 1)
>>>

>>
>>"Show" I changed the "Open" to "Show" and BINGO!
>
>Did you test it with PowerPoint installed?

Yes. And guess what - I get a "No association." error when PowerPoint is installed.
If I change the "Show" back to "Open" on the PowerPoint machine the program runs again.