I all. I have the following form used to temporarily upload a photo on a j2ee server and then crop it with imageAreaSelect plugin :

<form name="formAvatarName" id="formAvatar" method="post" 
action="../admin/admin-avatar-upload" 
enctype="multipart/form-data">
<label>Upload a Picture of Yourself</label>
<input type="file" name="upload" id="upload" size="20" />
<input type="button" id="formAvatarSubmit" value="formAvatar" onclick="invia()"/> 
</form>

I am using jquery form plugin to do ajax submission, this is my last :) attempt :

   $('#formAvatar').unbind('submit').bind('submit', function() {
     alert('aho');
        $(this).ajaxSubmit(options);
        return false;
   }); 

Only when tested with IE6 I can see that the sumbission to the server is done multiple times (first time I got the uploaded file, the other times the sumbmission seems empty and I got error). With IE7, IE8, FFOX, CHROME is working fine. Any Ideas? Many thank in advance!