Style display not working in Firefox, Opera, Safari - (IE7 is OK)

Actually I was experiencing the same problem you're describing here. What actually fixed my issue was changing the document properties.

Old DOCTYPE/html spec

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">

Replaced with

<html>

Found the answer : I need to use the following to make it work on both browsers :

document.getElementById('editRow').style.display = '';

Can you provide some markup that reproduce the error?

Your situation must have something to do with your code since I can get this to work on IE, FF3 and Opera 9.5:

function show() {
  var d = document.getElementById('testdiv');
  d.style.display = 'block';
}
#testdiv {
  position: absolute;
  height: 20px;
  width: 20px; 
  display: none;
  background-color: red;
}
<div id="testdiv"></div>
<a href="javascript:show();">Click me</a>

Since setting the properties with javascript never seemed to work, but setting using Firebug's inspect did, I started to suspect that the javascript ID selector was broken - maybe there were multiple items in the DOM with the same ID? The source didn't show that there were, but looping through all divs using javascript I found that that was the case. Here's the function I ended up using to show the popup:

function openPopup(popupID)
{
  var divs = getObjectsByTagAndClass('div','popupDiv');
  if (divs != undefined && divs != null)
  {
    for (var i = 0; i < divs.length; i++)
    {
      if (divs[i].id == popupID)
        divs[i].style.display = 'block';        
    }
  }
}

(utility function getObjectsByTagAndClass not listed)

Ideally I'll find out why the same item is being inserted multiple times, but I don't have control over the rendering platform, just its inputs.

So when debugging issues like this, remember to check for duplicate IDs in the DOM, which can break getElementById.

To everyone who answered, thanks for your help!