I have seent that PowerPoint will suppress the Screen
Saver when it is showing a presentation.

I would like to be able to do something similar in
VBScript. Is there a way that the screen saver can be
disabled (by VBScript) when a page is displayed and then
re-enabled when the page is unloaded?

That requires a Win32 API call and script clients can't access the API
calls, only COM methods.  You'll need to write you own ActiveX wrpper for
the API call or use a generic 3rd party API wrapper like Jim Warrington's
'wsh API ToolKit'.

wsh Utilities and Scripts Home Page [Jim Warrington]
http://home.att.net/~wshvbs/index.htm

and scroll down to "Calling API's from Script (gasp!)...".

--
Michael Harris
Microsoft.MVP.Scripting
Seattle WA US