Microsoft Word 2003

I have a client who brought a technical document to me that was acting
"strangely." It is over 500 pages, very little use of styles and lots of
direct formatting.

He doesn't know who wrote the original. He opened the original (Normal was
Times 12, all other styles looked OK), made some editing changes, and then
saved the file. However, when he opened the document the next time, many of
the styles were changed. Normal was now a font with a name that appears to
be in Chinese or Japanese characters. The heading styles are now
zapfdingbats. Sections that used to be code examples in Courier are now
formatted with Symbol.

I'm at a total loss of what has happened. I don't know if the document was
first written in Chinese or Japanese -- which accounts for the oddly named
font. I thought at first I could just reset Normal and things would be OK --
but that just resulted in other odd things happening -- like "blank
rectangles" now showing up for some characters.

Detect language automatically is not checked.
Styles are not selected to be udpated automatically.
Under Font Substitution, there is
Geneva - Arial
MS Mincho - Arial Unicode MS
Sim Sun - Arial Unicode MS
the odd named font - Aria Unicode MS

Any ideas on what has happened to this document? He was able to revert to
another version that doesn't exhibit this strange behaviour. Is there
anything we can do to keep this from happening again?

Thanks,
Rita
rhewell