New Post: XHTML special characters no longer render correctly

So, I've fixed the issue by updating the FixXhtmlFragment method in XhtmlTransformations.asmx to include

.Replace(" ", " ");

in:

    private static string FixXhtmlFragment(string xhtmlFragment)
        {
            xhtmlFragment = Regex.Replace(xhtmlFragment, @"(\s)\r\n</script>", "$1</script>", RegexOptions.Multiline);
            return xhtmlFragment.Replace("\xA0", "&#160;").Replace("&nbsp;", "&#160;").Replace("&amp;nbsp;", "&#160;");
        }

...but it seems like a hack, any ideas why this would happen in the first place?