Error for Telerik.Framwork.dll at time of Upgrade Sitefinity

The following error message get for Telerik.Framework.dll version "3.7.2136.340" in Bin folder is :
"Could not load file or assembly 'Telerik.Framework, Version=3.7.1990.2, Culture=neutral, PublicKeyToken=dfeaee0e3978ac79' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)"

To resolve above error I have added Telerik.Framework dll with version no. "3.7.1990.2" in Bin folder.Then
 following error message get for Telerik.Framework.dll version "3.7.1990.2" in Bin folder is :
 "CS1705: Assembly 'Telerik.Cms, Version=3.7.2136.340, Culture=neutral, PublicKeyToken=dfeaee0e3978ac79' uses 'Telerik.Framework, Version=3.7.2136.340, Culture=neutral, PublicKeyToken=dfeaee0e3978ac79' which has a higher version than referenced assembly 'Telerik.Framework, Version=3.7.1990.2, Culture=neutral, PublicKeyToken=dfeaee0e3978ac79'"

for resolve these issue I added following tag in web.config :
     <dependentAssembly>
        <assemblyIdentity  name="Telerik.Framework" publicKeyToken="dfeaee0e3978ac79" culture="neutral" />
        <bindingRedirect
                    oldVersion="3.7.1990.2"
                     newVersion="3.7.2136.340" />
      </dependentAssembly>
After adding above tag for dependentAssembly error related Telerik.Framwork is go away and gives error for Ambiguity of same name System.Web.Extensions.dll in
C:\WINDOWS\assembly folder and  C:\WINDOWS\Microsoft.NET\assembly\GAC_MSIL\System.Web.Extensions\v4.0
 
How to resolve this Ambiguity error.
Please also tell me if there is any other approch to resolve basic error related to Telerik.Framework.dll

Thanks
Vishal 

Hi Joshua Martyn,

It seems that your website is upgraded to SP4 .NET 4.0 however you still have projects which are using older Sitefinity assemblies. This is causing the error on your side. To resolve the problem please try removing the binding redirect from web.config. Then make sure that all Sitefinity assemblies in your website's bin folder are of version 3.7.2136.340. Finally open up your projects which use Sitefinity assemblies and fix the references so that they use the new versions. Rebuild your projects and add the rebuilt assemblies to your website's bin folder.

Regards,
Radoslav Georgiev
the Telerik team