Ajax not working in IE

[eluser]JasmineFlower[/eluser]
Hi,

Below code works fine on all browser except IE.If someone could help me in fixing this ,that would be really great!

Code:

function validatelogin()
{    
    var un=document.login_form.uname.value;
    var pw=document.login_form.pword.value;

    if(un == '')
    {
        document.getElementById('error_msg')[removed]="Enter the username";
        document.login_form.uname.focus();
        return false;
    }
    else if(pw == '')
    {
        document.getElementById('error_msg')[removed]="Enter the password";
        document.login_form.pword.focus();
        return false;
    }
    else
    {    
        $.ajax({
        type: 'POST',
        dataType: 'json',
        url: base_url + 'home/loginauth/' + Math.random(),
        data: 'uname=' + un+'&pword;=' +pw,
        success: function(response)
        {
            var urlcontent    = response.result;
            if(urlcontent == false)
            {
                document.getElementById('error_msg')[removed]="Invalid user name and password";
                return false;
            }
            else
            {                
                window.parent.location = 'welcome/index/';                
                return true;
            }                                    
        }
        
        });
        return false;

    }
    

}