Powerpoint does not understand the format of pictures you have imported. What picture type have you actually added to the slides? Can you open the picture outside of powerpoint? If so "save as" - type JPG and try an import again.
>>> You've saved images and other content with hard linked filepaths instead of embedding them in document.
That was my first thought too, Jim, but it should only apply if Andy has moved or deleted the relevant content on his hard drive.
(Note though that if the content is on an external drive, it's file path might have changed if that drive has been removed and then re-connected. e.g. a file which was previously located at D\:images might now be at E\:images instead if another external drive has been allocated D as its drive letter).
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