Thanks for all the help, guys. Kixum took the marbles on this one, tho. There were hidden keyframes within groups. The city walls were built in a seperate doc. and put into the browser, and from there brought into the city scene. Apparently the scrubber was set to 2 sec. in the wall doc. and things got moved around...keyframes got made. That's why no frames were visible in the city scene timeline.

So I went back to the wall doc., eliminated all keyframes, brought the new walls back into the browser, and everything's staying put. Couldn't ask for more.