Thanks Tobiah,
 
 

there's no loop points in the samples:
bad loop points.

I tried with a larger krate with the same result
rapid k-rate freq change.

I tried also an enveloppe for note-off
no envelope on note-off.

 I beleive it's the last reason invoked.

->Or, I have a set of AIFF files that have copyright
chunck at end.  As I remember, csound played the copyright
chunck very faithfully.  Sounded like a click though.

And it seems that the problem is in the middle of the sound
ANd my problematic sample was taken from a commercial CD. So how can we view the copyright chunk and edit it, although it's not really legal, it's just to confirm the problem which in this case is due to the sample and not to loscil?

Thanks
karim