#divFundoTransparente {
    background-color: gray;
    position:fixed;
    opacity: .4;
    z-index:98;
    width:100%;
    height:100%; 
    top:0; 
    left:0; 
}
#divProcessando 
{     
    background: url(imagens/carregando4.gif) no-repeat center;
    position:fixed; 
    z-index:99; 
    width:100%; 
    height:100%; 
    top:0; 
    left:0; 
}