Problem manipulating PowerPoint .pps files

Hi!

in short:
How can I open a pps file without immediately starting the slideshow?
or: how can I change the slide show settings of a pps file?

in detail:
I want to open a PowerPoint file and run the presentation with specific settings. For example I do not want the presentation to loop. This works with .ppt files, but not with pps files.

set theFile to choose file

tell application "Microsoft PowerPoint"
	activate
	open theFile
	
	set theSlideShowSet to slide show settings of active presentation
	set loop until stopped of theSlideShowSet to false
	run slide show theSlideShowSet
end tell

I think the problem is, that opening a pps file immediately starts the slideshow.
So, I tried

set theFile to choose file
tell application "Finder" to set theExtension to name extension of theFile

tell application "Microsoft PowerPoint"
	activate
	if theExtension is "ppt" then
		open theFile
		set theSlideShowSet to slide show settings of active presentation
		set loop until stopped of theSlideShowSet to false
		run slide show theSlideShowSet
		
	else if theExtension is "pps" then
		open theFile
		set loop until stopped of slide show settings of active presentation to false
	end if
end tell

but still the slideshow of the pps file ignors my command.

Does anybody know a way how to open a pps file without immediately starting the slideshow?
I realized, that double cklicking a pps file in the Finder starts the slideshow, while opening the same file via the open-dialog of PowerPoint opens it in a “normal” mode. But how can this be done via AppleScript?

Thanks in advance!

Rename it to *.ppt

HTH,
Gabriel.