Server Configuration Error Help Please - Parser Error Message: Only one <configSections> element allowed per config file and if present must be the fi

Have changed the <configuration> tag with the following;

<system.web>
        <customErrors mode="Off"/>
    </system.web>

Now I am getting the following error message when trying to run program on remote shared hosting service with MS SQL and .NET 4.0 installed;

Server Error in '/' Application.
Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: Only one <configSections> element allowed per config file and if present must be the first child of the root <configuration> element.

Source Error:

Line 4:      </system.web>
Line 5:  
Line 6:    <configSections>
Line 7:      <section name="NopConfig" type="NopSolutions.NopCommerce.BusinessLogic.Configuration.NopConfig, Nop.BusinessLogic" requirePermission="false"/>
Line 8:      <section name="urlrewritingnet" type="UrlRewritingNet.Configuration.UrlRewriteSection, UrlRewritingNet.UrlRewriter" requirePermission="false"/>

Can someone advise me as to what exactly I should change in the webconfig file to get this copy of 1.9 to load properly?  Or is it this virtual directory and IIS? Thanks in advance!

Mark