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.

View more information »

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