Error 404 - /_vti_bin/owssvr.dll and robots.txt

Question

Hi
My webstats tell me that I have had various Error 404s and
this is because of files being "required but not found":
specifically /_vti_bin/owssvr.dll and robots.txt.
Can someone tell me what these are?
Also, there are various other status code pages coming up
such as
302 Moved temporarily (redirect) 6 27.2 % 2.79 KB
401 Unauthorized 5 22.7 % 9.32 KB
403 Forbidden 3 13.6 % 5.06 KB
206 Partial Content
Why are these arising and how can I rid myself of them?
Many thanks : )

Answer 1

Example of httpmodule that uses the PreRequestHandlerExecute and how to return if it encounters the owssvr.dll
 class MyHttpModule : IHttpModule, IRequiresSessionState
   public void Init(HttpApplication context)
            context.PreRequestHandlerExecute += new EventHandler(context_PreRequestHandlerExecute);
  void context_PreRequestHandlerExecute(object sender, EventArgs e)
  if (app.Context.Request.Url.AbsolutePath.ToLower().Contains("owssvr.dll"))
                    return;