If you use ASP.NET as a Remoting client, you should not use this code in your app.config:
protected void Application_Start(Object sender, EventArgs e)
{
RemotingConfiguration.Configure(Server.MapPath("client.exe.config"));
}
Using Server.MapPath(), some requests might fail if the application is recycled and the first request is not for a file in the application's root directory but in a subdirectory (i.e. "http://yourhost/somedir/default.aspx" instead of "http://yourhost/default.aspx". Robert suggested to use the following (and of course, he's totally right):
protected void Application_Start(Object sender, EventArgs e)
{
RemotingConfiguration.Configure(Request.PhysicalApplicationPath
+ "client.exe.config");
}