Thanks for the response, folks. Unfortunately I can no longer recreate what was happening before, but something has changed. When I would select audio to send out to an editor before (using the methods described above -- I'm sure of that), it would take several seconds to render the audio, and it would open in my external editor as a large sound file, including several minutes' worth of audio, depending on the size of the video project. Now it will only open a few seconds of audio for the current scene.

Hmmmm. Maybe I was just dealing with really long scenes before, and only thought I was getting all of the audio for the project when I was really only getting the one scene. I guess that must have been it.

One other question while we're on the subject -- does anyone know whether there's a way to split audio tracks in the basic (non-pro) version of Vegas 6.0 to allow fading? I have some traffic noise in the middle of a scene and so far can find no way to fade the audio only for one section of a scene. I suppose I may just need to edit the audio externally. Are there any other workarounds? Thanks.