A PowerPoint import error

This may be because there is a corrupt element on a page in the PowerPoint file.
Open the PowerPoint file and check it over carefully. It may be that the Notes field contains corrupt elements. If the Notes on a page are empty, try keying in a character and deleting it again before trying to re-import the file.

Alternatively, there may be a link in the PowerPoint file to another file, e.g. an Excel file. Remove any such links from the PowerPoint file and try to import the file again.