It is not an upgrade, it's a a fresh install of Xoops 2.5.3.
I use Maxthon browser. But I have the same problem with Internet Eplorer.
<head>
<!-- Assign Theme name -->
<!-- Title and meta -->
<meta http-equiv="content-language" content="en" />
<meta http-equiv="content-type" content="text/html; charset=UTF-8" />
<title>Just Use it! - XOOPS Site</title>
<meta name="robots" content="index,follow" />
<meta name="keywords" content="xoops, web applications, web 2.0, sns, news, technology, headlines, linux, software, download, downloads, free, community, forum, bulletin board, bbs, php, survey, polls, kernel, comment, comments, portal, odp, open source, opensource, FreeSoftware, gnu, gpl, license, Unix, *nix, mysql, sql, database, databases, web site, blog, wiki, module, modules, theme, themes, cms, content management" />
<meta name="description" content="XOOPS is a dynamic Object Oriented based open source portal script written in PHP." />
<meta name="rating" content="general" />
<meta name="author" content="XOOPS" />
<meta name="copyright" content="Copyright @ 2001-2011" />
<meta name="generator" content="XOOPS" />
<!-- Rss -->
<link rel="alternate" type="application/rss+xml" title="" href="http://www.cesag.byethost3.com/e/backend.php" />
<!-- Favicon -->
<link rel="shortcut icon" type="image/ico" href="http://www.cesag.byethost3.com/e/themes/default/icons/favicon.ico" />
<link rel="icon" type="image/png" href="http://www.cesag.byethost3.com/e/themes/default/icons/favicon.png" />
<!-- Sheet Css -->
<link rel="stylesheet" type="text/css" media="all" title="Style sheet" href="http://www.cesag.byethost3.com/e/xoops.css" />
<link rel="stylesheet" type="text/css" media="all" title="Style sheet" href="http://www.cesag.byethost3.com/e/themes/default/style.css" />
<!--[if lte IE 8]>
<link rel="stylesheet" href="http://www.cesag.byethost3.com/e/themes/default/styleIE8.css" type="text/css" />
<![endif]-->
<!-- customized header contents -->
<script src="http://www.cesag.byethost3.com/e/include/xoops.js" type="text/javascript"></script>
<link rel="stylesheet" href="http://www.cesag.byethost3.com/e/language/english/style.css" type="text/css" />
</head>
Please see my website (to make tests) here :
http://www.cesag.byethost3.com/e/