Hi Michelle
The 2 places I would start looking for a solution to the issue are fonts &
printer drivers.
Fonts
The font(s) used in a presentation must be installed on the destination
computer or they will be replaced by PowerPoint. This can lead to display
problems. Some fonts can be embedded but that comes with its own set of
issues:
Embedding fonts
http://www.pptfaq.com/FAQ00076.htm
Printer Drivers
This is an issue specific to 2007 and is not about printing. Honestly
PowerPoint 2007 text editing slow, text cut off, text display or formatting
problems, print, crash problems
http://www.pptfaq.com/FAQ00850.htm
Hopefully that will get you started. If your friends are still having
problems, post back with specifics about their set-up, the problem
computers' set-ups, details about the presentations etc.
Lucy