I guess for some reason you need to use the unselectAll that seem to work:
function doChapters(){
if ($('#c4').is(":visible")){
$('#c4').hide();
}
else{
chaptersw=0; //select chapter mode
memberid = document.getElementById("m_id").value;
$("#mem_id").val(memberid);
fname = document.getElementById("fname").value;
$("#f_name").val(fname);
lname = document.getElementById("lname").value;
$("#l_name").val(lname);
$('#c4').show();
$("#c4").css('zIndex', 9999);
$('#ci').datagrid('load');
$('#ci').datagrid('unselectAll'); //clear selected
}
}