I've downloaded the control again. I created a test application and tested it. It works fine. So I copied the control files to an existing site and created a test page with a control and get the same result. test page code below:
<%@ Page Language="VB" %>
<%@ Register Assembly="CuteEditor" Namespace="CuteEditor" TagPrefix="CE" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<ce:editor id="Editor1" runat="server"></ce:editor>
</div>
</form>
</body>
</html>