Geoff,
Is the annotation over the PowerPoint file being done with ActivInspire’s Annotate Over Desktop Feature or with the use of the Promethean ActivOffice Plug-in for Microsoft PowerPoint?
If the former is the case, does any other software close unexpectedly while being annotated upon or does the same issue present while any other user logs in to this computer and performs the same actions? Can you also confirm the version of ActivInspire in use on the computers in question?
If the latter, is the can you confirm which version of Microsoft office is installed on the computer and whether that version is 32 or 64-bit?