Popping sounds at end of clips

Hey

I'm using Audition CS6 (windows) and I'm getting these click/pop sounds at the end of clips in multitrack. If I open the individual clips up to edit and play it through there isn't any sign of it. However if I play the clip through in edit mode and stop it near the point where the pop is I will hear the pop when I hit stop. The irritating thing is if I do a mix down these little errors are still there and they are pretty loud!

Any idea what could cause this? I'm using windows 7 and Cs6.

G