Microsoft uses different default fonts in the 2007 file formats, do you know if the font that the document had been using exists on the systems you were using? The system may have done a substitution, and not known what to do with some of the unicode characters, despite the fact that they probably existed in Times or another font that was already on the 2400c.

What I'd try is making sure all of the fonts that are in use on the work computers are installed on the 2400c, or that your document comes to the 2400c that's already installed on it.