Andrew,
Thanks! I didn't get any kind of results from Ctrl-Space/Ctrl-Q. What is that supposed to do?
I did indeed find instances in the corrupt document where the user had applied other formatting, such as bold & font size changes. This created a modified version of my original style that I could see in the full style window.
If this is what triggers the corruption I will have to find a way to prevent users from applying their own formatting to paragraphs set by my styles, or just live with the infrequent occurrence if that's not possible.
Thanks again for the assistance. I appreciate your time.
~ Phil