Pro 18 on Windows 10 PC.

I am trying to make a copy of an interview on a Blu-ray disc for the subject, whom I interviewed some years ago. The video and audio were saved as separate files, the first as mv2, the latter as AC3. I figured I'd just put them in Vegas, synch them up, render as an mp4, and burn a disc.

I copied both files to my desktop and then imported them into Vegas project media and added to the timeline.The video has silent titles, so I need to synch the audio at the beginning. I am dragging the audio in its track to match up with the subject's first speech, which takes some trial and error.

It begins to work, but then the audio begins self-duplicating small bits of audio, although I don't see a change in the track. That is, I hear a repetition of a bit of a phrase after moving the audio event, even though it doesn't correspond with what I am seeing on the track. This is repeated each time I move the event. If I delete the audio track from the timeline, there is no audio, but I have no idea where the "ghost audio" is coming from, or why it is being created. I have never have had any such thing happen before. In any case, trying to synch the two is impossible. I tried deleting the audio from the project and reimporting, which got things back to square one, but then the same thing began happening.

Anyone know what could be causing this?

Thank you.