I have to confess I am bemused by the error you have, since I can't replicate it. Everything works perfectly on our servers, with FireFox and Safari. I'll test again IE later.

Whats odd. Is that in our code we already have

latex = latex.replace(/\\/g,'\\\\');

as in:

if(latex!==undefined)
	{
	  latex=unescape(latex);
	  latex = latex.replace(/\\/g,'\\\\');
          latex = latex.replace(/'/g,'\\'');
          latex = latex.replace(/"/g,'\\"');
          latex = latex.replace(/0/g,'\\0');
 
	  eval("var old = popupEqnwin.document.getElementById('JSONload')");
	  if (old != null) {
	    old.parentNode.removeChild(old);
	    delete old;
	 }
 
	var head = popupEqnwin.document.getElementsByTagName("head")[0];
	var script = document.createElement("script"); 
	script.type = "text/javascript";  
	script.id = 'JSONload';
	script.innerHTML = 'EqEditor.load(''+(latex)+'');';
	head.appendChild(script);
    }

So why isn't this working for you. Why do you have to do it twice?

Do you know if this is specific to a particular browser?