Document.all not supported in FF

I have the following JavaScript, which reveals a hidden div in IE:

var menuOpenFlag = false;

openMenu = function(menu) {
    for (i=0; i>9; i++) {
        document.all['menu*'].style.display = 'block';

Never mind, got a solution.
closeAll = function() {
    document.all['menu1'].style.display = 'none';
    document.all['menu2'].style.display = 'none';
    document.all['menu3'].style.display = 'none';
    document.all['menu4'].style.display = 'none';
    document.all['menu5'].style.display = 'none';
    document.all['menu6'].style.display = 'none';
    document.all['menu7'].style.display = 'none';
    document.all['menu8'].style.display = 'none';
    document.all['menu9'].style.display = 'none';

Here’s the code for the links that activate the hidden div:

onmouseover="javascript:if (menuOpenFlag == false) {closeAll(); document.all['menu2'].style.display = 'block';}"

The problem is, it doesn’t work in FF or Safari. document.all is not recognized by FF or Safari. I’ve been poking around and have found a few scripts that check browser versions for handling, but nothings clear on this.

Any ideas?