It's a common bug. Turn off music before entering (you can turn it back on later).

You'll need to have the music off each time you load a save that is within the palace, as well.

You can load a save outside the palace and turn the music off, then load a save inside the palace (and then turn the music back on, if you are so inclined). Important thing is that the music is off any time the Eschaton's Palace map is loaded.

Thanks guys!! That nailed it. Odd that I never ran into it before in 18 years of play. Must be the GOG version of the game. Various versions had other problems (on later OS) however. I am not complaining and will apply the discipline to avoid this one.

Thanks again

The disc version didn't have this issue (at least my disc version didn't); it is something about the GOG version.