Actually, I have them both inside a Microsoft folder, and just in the Preferences folder. I've moved one from each location and fired up the corresponding program. The one that gets "rebuilt" is inside the Microsoft folder. The path I gave (post #5) is not a typo. I didn't type it. I opened the folder, found the plist file and used drag 'n drop to this window, which produces the full path for me.
I have that Office 2008 folder as well. (For the life of me, I don't know why. I have O4M 2004!) But the plists files are right there alongside that Office 2008 folder, not buried further "up the tree". However, there might be a difference between 2004 and 2008 as far as where those pesky files are kept. You have, them, guaranteed. What I can't guarantee is that following my suggestion will solve the problem. I'm hoping to learn more about the contents of plist files, so it's just a trial and error idea, kind of like a doctor prescribing medications.