output WAV file contains woblling sound

Hello there,
 
    I have ported Madlib on Palm OS platform.I am using the 'FPM_DEFAULT'
setting for using the Madlib library because usng any other setting the
Codewarrior compiler gives an error.The program runs fine but the output WAV
file which I am writing conatins wobbling sound.The tune for the song is
fine but the output wobbles a lot. I wanted to know whethe this is due to
the FPM_DEFAULT setting we are using ,if not then what could be the reason
for this kind of output.
 
Regards,
Swapnil