Or, if you don't have an option for appPool type but you do know it to be hosted on Windows 2008, then paste this into the very bottom of your Web.config, but inside the </configuration> tag file and it may solve it.
<system.webServer>
<!-- this section only applies to IIS 7-->
<validation validateIntegratedModeConfiguration="false"/>
<modules>
<add name="GCheckoutBasicAuthenticationModule" type="mojoPortal.Web.GCheckoutBasicAuthenticationModule, mojoPortal.Web" />
<add name="BannedIPBlockingHttpModule"
type="mojoPortal.Web.BannedIPBlockingHttpModule, mojoPortal.Web"/>
<add name="UrlRewriter" type="mojoPortal.Web.UrlRewriter, mojoPortal.Web" />
<!-- AJAX Extensions support -->
<add name="ScriptModule" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
</modules>
</system.webServer>
Maybe restore the System.Web.Extensions.dll if it complains about it missing.
Best,
Joe