A little something about everything

This method can be used to fix duplicate content errors and make it so google only indexes one version of your urls, which will prevent you from getting a negative modifiers.

In order to do this you have two options.

1. Use the proper canonical tags, for example place the following code at the top of your website:
   <link rel="canonical" href="http://(yourdomain).(tld)/Your-Special-Directory-With-Whatever-Case-You-Want" />
2. Use the following script to automate the process and only allow lower case urls to be viewed on your site, create a global.asax file and place it in your site's main directory. 
   <script language="C#" runat="server"> protected void Application_BeginRequest(Object sender, EventArgs e) { if (Regex.IsMatch(HttpContext.Current.Request.Url.ToString(), @"[A-Z]")) { // Lowercase url String lower = HttpContext.Current.Request.Url.ToString().ToLower(); // Redefine response HttpContext.Current.Response.Clear(); HttpContext.Current.Response.Status = "301 Moved Permanently"; HttpContext.Current.Response.AddHeader("Location", lower); HttpContext.Current.Response.End(); } } </script>

If you plan to use both methods be sure to use only lower case for your canonical tags or you will end up with problems.