From VB: http://www.rdpslides.com/pptfaq/FAQ00580.htm

The honest truth: http://www.rdpslides.com/pptfaq/FAQ00611.htm

In particular, this part:

Code That Runs Automatically
Some Office applications have a way to run VBA code automatically when the user opens a document; not PowerPoint.

But an Auto_Open subroutine within an Add-in will run at the time the Add-in loads, so IF you can create an Add-in and install it on the user's computer Create an ADD-IN with TOOLBARS that run macros then
The Add-in can respond to events - Make PPT respond to events
  • It can detect things like "The user just opened a presentation".
  • You could use this and some extra code to detect that "The user just opened OUR presentation" and run any other code you like in response.