Ajax仅工作几次

when i click on navigation(home etc) its working perfectly but only 2 or three times.when i click again on he navigation the image i stop loading(not displaying). thanks for your answers.

JS

$(document).ready(function(){
    $(document).ajaxStart(function(){
        $("#loading").show();
    });
    $(document).ajaxComplete(function(){
        $("#loading").fadeOut();
    });
    $("ul li a").click(function(e){
        e.preventDefault();
        abc=$(this).attr("href");
        $(".right-content").load(abc);
    }); //`enter code here`
});

HTML

<div id="nav">  

    <ul>
        <li><a href="abc.php">Home</a></li>
        <li><a href="abc.php">About Us</a></li>
        <li><a href="form.php">Add Page</a></li>
        <li><a href="abc.php">Contact-Us</a></li>
        <li><a href="new_index.php">Login</a></li>
        <li><a href="signup.php">Sign-Up</a></li>
        <li><a id="log" href="logout.php">
    </ul>
</div>

IMG

<div id="loading" style="display:none;width:69px;height:89px;border:1px solid black;position:absolute;top:50%;left:50%;padding:2px;">
<img src='loading.gif' width="64" height="64" /><br>Loading..</div>

You haven't closed your tag properly at logout anchor. That might be causing problem;

Replace

<li><a id="log" href="logout.php">

with

<li><a id="log" href="logout.php">Logout</a></li>

See working demo: http://jsfiddle.net/bLUZM/