Audio Mixdown issue

I hit an unusual audio mixdown error last night. Cubase 6-5 under windows 7 32bit.

I import a wave file extracted from a video into a blank cubase session, The audio file extraction was done outside of cubase.
I duplicate the track.
I add 4 group tracks to the project so I can apply send effects to the two audio tracks in the project.
After completing the mix I then use the audio mixdown dialog to export a single wave file from the stereo output bus only.
This worked OK for a couple of sessions with the final wav file being same time length as the original wav file.

However the third time I tried this the resultant exported wave file was 18 seconds longer than the original audio file (This is a problem as the file is required to match a video track).

I have ensured the output bit rate for mixdown is identical to that of the source file.

Anyone seen this or have any clues, suggestions what may be happening here. I cant understand why the audio file would increase in length during mixdown.



Well the only logical explanation would be that you’ve accidentally moved the right locator befor mixdown. If you’re absolutely sure that you didn’t, then I really don’t know.

How does the bad file look if you reimport it to Cubase, is the audio stretched, is there silence added in the beginning or the end?