Hosting ASP.NET site in IIS 7

I was hosting published site in IIS 7 on Windows 7 installed machine. I had done setting for .NET framework version, Security Options but got Error as shown below

HTTP Error 500.19 - Internal Server Error

The requested page cannot be accessed because the related configuration data for the page is invalid. Detailed Error Information Module IIS Web Core Notification BeginRequest

Handler Not yet determined

Error Code 0x800700b7

Config Error There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined

Config File \?\D:\inetpub\wwwroot\KDAHCSSD\web.config

Requested URL http://localhost:80/KDAHCSSD/frmLogin.aspx

Physical Path D:\inetpub\wwwroot\KDAHCSSD\frmLogin.aspx

Logon Method Not yet determined

Logon User Not yet determined

Config Source 13:
sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"

14: section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" allowDefinition="MachineToApplication"/

15: sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"

Links and More InformationThis error occurs when there is a problem reading the configuration file for the Web server or Web application. In some cases, the event logs may contain more information about what caused this error.

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How to solve this. What will I need to do?..

Assuming you are running a .Net 4 site, the machine.config will already have defined the scriptResourceHandler. Remove this section from the web.config and you should be fine.

EDIT: Just noticed you say you are running 3.5 and so shouldn't happen, but try removing that section and see if it works.