well
    yes i'm on 8.1us system, and i already tried it on 7.6.1 with the
same results. so i don't think it's due to Macos system.
    I tried it with Aiff  & sound designer format . As for the header I
don't know if it's included (I mean the sound file header, and not the
sr=441000, etc... Csound header.)
As for the disk space i have 1.5 Giga free, and i did defragment the
disk!
    I tried a lot of stuff just to see what was wrong. Even swiched
disk. BUT the error seems to concern only some kind of scores! Bizzare i
say!
    I will investigate further on, and hope i can detect it with my
limited knowledge.
Yes i have allocated 30000k of ram to the Perf!
    One thing i don't know about is "headerless/raw" ? maybe that is the
main problem!

    Thanks to you all for responding to my prob. I 'll send the output
of the perfing!

    Karim