Nevermind, I figured it out. If anyone else is struggling with this issue, I think it's the combination of using cleditor, the XHTML plugin and Internet Explorer.
You can fix it by adding this JavaScript Snippet before your cleditor code:
(function ($) {
var oldCallback = $.cleditor.defaultOptions.updateTextArea;
$.cleditor.defaultOptions.updateTextArea = function (html) {
if (oldCallback) {
html = oldCallback(html);
}
var isIE = /*@cc_on!@*/false;
if (isIE) {
return html.replace(/\\\"/g, """);
} else {
return html;
}
};
})(jQuery);
Alternatively, you can do the conditional replacement in jquery.cleditor.js (line 1126 for cleditor v1.3.0).