After doing some more research (stumbling upon a relevant search string, to tell the truth) it seems that Add-ins can contribute to the behavior I have described. I will go through my Add-ins to see if I can identify a culprit. There is a kb article on the topic (921541), but it only describes tracking down the Add-in, and not what changes need to be made with that Add-in. It also seems to assume that Add-ins come from third party vendors (it advises to "contact the vendor of the add-in for an update"). I use Add-ins for styles and macros, and leave the Normal template alone for the most part. I could probably do away with the styles Add-in, since I can retrieve the styles from a template, or else switch the document's basis to that template.