playing multiple files at once

I am experiencing RB  sometimes playing 2 or 3 or 4 files at once.
tracks are not just overlapping, they are all starting at the same time.
- version 5.8.07
- using scheduler to generate a playlist
- using Playlist Generator Pro to create a playlist based on my rules
- track overlap is always set to 0

Do you have an idea why some tracks are starting at the same time or when the previous file is not finished?

Please click Settings->Crossfades, and disable the Trigger mix at option, this should fix the problem.

That seems to have fixed the problem. THANK YOU !