XML Parsing Error: no element found firefox iis 7.5 asp.net 4 published

[dragstore]

I have a web application that was written with ASP.NET 4 C#. I published my app an moved it to my server(another computer). I have many sites that are working in my server with an application pool(.NET 2 and integrated) perfectly. I created an application pool(.NET 4 & integrated) for my new site. I added ASP.NET 4 ISAPI and CGI restriction in IIS.Now when I browse any pages of my new site I get this error in FireFox(XML Parsing Error: no element found location:.....) and this one in IE(HTTP 500 Internal Server Error...)Is there any setting that I forgot it?