this is my web.config and system.web.extensions show up multiple times so not 100% sure and i did not modify this file, it is the file the installation put in:
<?xml version="1.0"?>
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
<configSections>
<sectionGroup name="system.web.extensions" type="System.Web.Configuration.SystemWebExtensionsSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
<sectionGroup name="scripting" type="System.Web.Configuration.ScriptingSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
<section name="scriptResourceHandler" type="System.Web.Configuration.ScriptingScriptResourceHandlerSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication" />
<sectionGroup name="webServices" type="System.Web.Configuration.ScriptingWebServicesSectionGroup, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35">
<section name="jsonSerialization" type="System.Web.Configuration.ScriptingJsonSerializationSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="Everywhere" />
<section name="profileService" type="System.Web.Configuration.ScriptingProfileServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication" />
<section name="authenticationService" type="System.Web.Configuration.ScriptingAuthenticationServiceSection, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" requirePermission="false" allowDefinition="MachineToApplication" />
</sectionGroup>
</sectionGroup>
</sectionGroup>
<!-- Content staging BEGIN -->
<section name="microsoft.web.services3" type="Microsoft.Web.Services3.Configuration.WebServicesConfiguration, Microsoft.Web.Services3, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<!-- Content staging END -->
</configSections>
<appSettings>
<add key="CMSProgrammingLanguage" value="C#" />
<add key="CMSTrialKey" value="CE03-20090228-oSKFCE" />
<add key="WS.webservice" value="http://localhost/WebService/webservice.asmx" />
<add key="CMSUseIFrameForHTMLEditorToolbar" value="true" />
<add key="CMSDefaultSpellCheckerCulture" value="en-US" />
<add key="CMSRenderGeneratorName" value="true" />
</appSettings>
<connectionStrings>
<clear />
</connectionStrings>
<system.web>
<pages validateRequest="false">
<controls>
<add tagPrefix="asp" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<add tagPrefix="ajaxToolkit" namespace="System.Web.UI" assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<add tagPrefix="ajaxToolkit" namespace="AjaxControlToolkit" assembly="AjaxControlToolkit" />
<add tagPrefix="cms" namespace="CMS.Controls" assembly="CMS.Controls" />
<add tagPrefix="cms" namespace="CMS.FormEngine" assembly="CMS.FormEngine" />
<add tagPrefix="cms" namespace="CMS.ExtendedControls" assembly="CMS.ExtendedControls" />
<add tagPrefix="cms" namespace="CMS.PortalControls" assembly="CMS.PortalControls" />
</controls>
<namespaces>
<add namespace="CMS.CMSHelper" />
<add namespace="CMS.GlobalHelper" />
</namespaces>
</pages>
<customErrors defaultRedirect="~/CMSMessages/error.aspx" mode="Off">
<error statusCode="404" redirect="~/CMSPages/handler404.aspx" />
</customErrors>
<authentication mode="Forms">
<forms loginUrl="CMSPages/logon.aspx" defaultUrl="Default.aspx" name=".ASPXFORMSAUTH" timeout="60000" slidingExpiration="true" />
</authentication>
<httpRuntime maxRequestLength="10000" />
<globalization requestEncoding="utf-8" responseEncoding="utf-8" culture="en-US" uiCulture="en-US" />
<membership defaultProvider="CMSProvider" userIsOnlineTimeWindow="30">
<providers>
<clear />
<add name="CMSProvider" type="CMS.MembershipProvider.CMSMembershipProvider" connectionStringName="CMSConnectionString" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="true" passwordFormat="Hashed" />
</providers>
</membership>
<roleManager defaultProvider="CMSRoleProvider" enabled="true" cacheRolesInCookie="true" cookieName=".ASPROLES" cookieTimeout="30" cookiePath="/" cookieRequireSSL="false" cookieSlidingExpiration="true" cookieProtection="All">
<providers>
<clear />
<add name="CMSRoleProvider" type="CMS.MembershipProvider.CMSRoleProvider" connectionStringName="CMSConnectionString" applicationName="SampleApplication" writeExceptionsToEventLog="false" />
</providers>
</roleManager>
<httpHandlers>
<remove verb="*" path="*.asmx" />
<add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" validate="false" />
</httpHandlers>
<httpModules>
<add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<add name="XHtmlModule" type="CMS.CMSOutputFilter.OutputFilterModule, CMS.OutputFilter" />
</httpModules>
<xhtmlConformance mode="Strict" />
<sessionState mode="InProc" stateConnectionString="tcpip=127.0.0.1:42424" sqlConnectionString="data source=127.0.0.1;Trusted_Connection=yes" cookieless="false" timeout="20" />
<compilation debug="false" numRecompilesBeforeAppRestart="100">
<assemblies>
<add assembly="System.Management, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
<add assembly="System.Windows.Forms, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
<add assembly="System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
<add assembly="System.Security, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
<add assembly="System.Configuration.Install, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
<add assembly="System.DirectoryServices, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
<!-- <add assembly="System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
<add assembly="System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
<add assembly="System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
<add assembly="System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
<add assembly="System.Xml, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
<add assembly="System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/> -->
<add assembly="System.Web.Extensions.Design, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<add assembly="System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
<add assembly="System.Data.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
<add assembly="System.Xml.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
</assemblies>
<!-- Different programming languages BEGIN -->
<!--<codeSubDirectories>
<add directoryName="CSCode"></add>
<add directoryName="VBCode"></add>
</codeSubDirectories>-->
<!-- Different programming languages END -->
</compilation>
</system.web>
<system.codedom>
<compilers>
<compiler language="c#;cs;csharp" extension=".cs" compilerOptions="/warnaserror-" warningLevel="4" type="Microsoft.CSharp.CSharpCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
<providerOption name="CompilerVersion" value="v3.5" />
</compiler>
<compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" compilerOptions="/optioninfer+" type="Microsoft.VisualBasic.VBCodeProvider, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
<providerOption name="CompilerVersion" value="v3.5" />
</compiler>
</compilers>
</system.codedom>
<!-- Windows authentication BEGIN -->
<!--
<location path="">
<system.web>
<authorization>
<deny users="?"/>
</authorization>
</system.web>
</location>
-->
<!-- Windows authentication END -->
<!-- Content staging BEGIN -->
<microsoft.web.services3>
<security>
<securityTokenManager>
<add type="CMS.Staging.WebServiceAuthorization" namespace="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" localName="UsernameToken" />
</securityTokenManager>
<x509 allowTestRoot="true" verifyTrust="true" />
</security>
<policy fileName="wse3policy.config" />
<diagnostics>
<trace enabled="false" input="InputTrace.webinfo" output="OutputTrace.webinfo" />
</diagnostics>
</microsoft.web.services3>
<!-- Content staging END -->
<system.webServer>
<validation validateIntegratedModeConfiguration="false" />
<modules>
<add name="ScriptModule" preCondition="integratedMode" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<add name="XHtmlModule" type="CMS.CMSOutputFilter.OutputFilterModule, CMS.OutputFilter" />
</modules>
<handlers>
<remove name="WebServiceHandlerFactory-Integrated" />
<add name="ScriptHandlerFactory" verb="*" path="*.asmx" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<add name="ScriptHandlerFactoryAppServices" verb="*" path="*_AppService.axd" preCondition="integratedMode" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
<add name="ScriptResource" preCondition="integratedMode" verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" />
</handlers>
</system.webServer>
</configuration>