Ogg Vorbis in Directsound - Access violation when locking and unlocking buffer

I am implementing ogg support for my audio engine.  I have retrieved the ogg info using vorbis_info, and everything is okay.  When I got to lock (or unlock) the directsound buffer in order to read in the ogg data, I receive an access violation.  I can't find any reason why the following code doesn't work.

Any help would be much appreciated.

      pDS->CreateSoundBuffer( &desc, &pTemp, NULL );

      DWORD      size      =      BUFSIZE;
      DWORD      pos            =      0;
      int            sec            =      0;
      int            ret            =      1;

    char    *buf;
    char    *buf2;

   
      pTemp->Lock( 0, size, (LPVOID*)&buf, &size, NULL, NULL, DSBLOCK_ENTIREBUFFER);
   
    // now read in the bits
    while(ret && pos<size)
    {
        ret = ov_read(&vf, buf+pos, size-pos, 0, 2, 1, &sec);
        pos += ret;
    }

    pTemp->Unlock( buf, size, NULL, NULL );