crash in sendtohelper

Dear Gurus,

I have one super-bug, that I just found

SendTo(data,length,PORT_VIDEO_A,CVideoConfInt::IPtemp1);

will give crash in:

_AFXSOCK_INLINE int CAsyncSocket::SendTo(const void* lpBuf, int
nBufLen, const SOCKADDR* lpSockAddr, int nSockAddrLen, int nFlags)
    { return SendToHelper(lpBuf, nBufLen, lpSockAddr, nSockAddrLen,
nFlags); }

only everytime I call:
(audio send)

//send audio data to server, invoked by record thread //recordsound
void CVideoConfInt::sendMessage(char* mesg, int length)
{
    char buflen[30];
    char str[PLAYBUFFER+100];
    int i,j;

    If user not selected or no users are present return;
    if(selectflag==0 )
        return;

    if(mesg==NULL)
    {
        log.WriteString("\nEmpty buffer received from recordsound");
        return;
    }

    if(length<1 || length>PLAYBUFFER)
    {
        log.WriteString("\n Send : Length is more than the 2000 or less than
1");
        return;
    }

    mesg=mesg-20;

    //First 15 bits contains the destination information
    //Next 5 bits contains the length of message
    //Remaining part contains the data

    if(curuser.IsEmpty())
    {
        log.WriteString("\n Curuser is Empty- No user selected");
        return;
    }

    for(i=0;i < curuser.GetLength();i++)
        mesg[i]=curuser[i];

    sprintf_s(buflen,"%d",length);

    for(j=0,i=15;j<5;j++,i++)
        mesg[i]=buflen[j];

    //Write to log file
    sprintf_s(str,"\n Sending message datalen = %d , mesg =
%s",length,&mesg[20]);
    log.WriteString(str);

    if(daudio.Send(mesg,length+20)!=SOCKET_ERROR )
        log.WriteString("\n Data sent successfully to "+curuser);
    else
        log.WriteString("\n Data sent Error ");
return;

}
void CVideoConfInt::startBufferWrite()
{
    if(record->recording==FALSE)
    {
// if(sockclt.name.CompareNoCase("logname")==0)
        record->PostThreadMessage(WM_RECORDSOUND_STARTRECORDING,0,0);
    }
}
void CVideoConfInt::stopBufferWrite()
{
    if(record->recording==TRUE)
        record->PostThreadMessage(WM_RECORDSOUND_STOPRECORDING,0,0);
}
void CVideoConfInt::startBufferPlay()
{
    play1->PostThreadMessage(WM_PLAYSOUND_STARTPLAYING,0,0);
    play2->PostThreadMessage(WM_PLAYSOUND_STARTPLAYING,0,0);
    play3->PostThreadMessage(WM_PLAYSOUND_STARTPLAYING,0,0);
    play4->PostThreadMessage(WM_PLAYSOUND_STARTPLAYING,0,0);
}
void CVideoConfInt::stopBufferPlay()
{
    play1->PostThreadMessage(WM_PLAYSOUND_STOPPLAYING,0,0);
    play2->PostThreadMessage(WM_PLAYSOUND_STOPPLAYING,0,0);
    play3->PostThreadMessage(WM_PLAYSOUND_STOPPLAYING,0,0);
    play4->PostThreadMessage(WM_PLAYSOUND_STOPPLAYING,0,0);
}

What seems to be the problem since I couldn't find any article related
to it?