How to use System.Configuration.DpapiProtectedConfigurationProvider version 2 in .net framework 4.5?

I recently upgraded my application from .net 3.5 to .net 4.5 .I maintain a config file in which I store user data.And that data is encrypted using System.Configuration.DpapiProtectedConfigurationProvider,System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a

After, upgrading when I tried to access data from the config file, it gave following error:

The entry 'DataProtectionConfigurationProvider' has already been added.

So, I removed the entry from the DataProtectionConfigurationProvider entry from the file.After that when I tried to access the file, I got following exception:

Failed to decrypt using provider 'DataProtectionConfigurationProvider'. Error message from the provider: Key not valid for use in specified state. (Exception from HRESULT: 0x8009000B)

Here is my config file:

<?xml version="1.0" encoding="utf-8"?>
<configuration> 
  <configSections>
    <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089">
      <section name="CustomPane_outlookAddIn.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    </sectionGroup>
  </configSections>
  <system.serviceModel>
    <bindings />
    <client />
  </system.serviceModel>

  <configProtectedData>
    <providers>
      <add name="DataProtectionConfigurationProvider" type="System.Configuration.DpapiProtectedConfigurationProvider,System.Configuration, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" description="Uses CryptProtectData and CryptUnProtectData Windows APIs to encrypt and decrypt" useMachineProtection="true" keyEntropy="" />      
    </providers>
  </configProtectedData>

  <appSettings configProtectionProvider="DataProtectionConfigurationProvider">
    <EncryptedData>
      <CipherData>
        <CipherValue>Encrypted user data</CipherValue>
      </CipherData>
    </EncryptedData>
  </appSettings>
  <system.web>
    <membership defaultProvider="ClientAuthenticationMembershipProvider">
      <providers>
        <add name="ClientAuthenticationMembershipProvider" type="System.Web.ClientServices.Providers.ClientFormsAuthenticationMembershipProvider, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" serviceUri="" />
      </providers>
    </membership>
    <roleManager defaultProvider="ClientRoleProvider" enabled="true">
      <providers>
        <add name="ClientRoleProvider" type="System.Web.ClientServices.Providers.ClientRoleProvider, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" serviceUri="" cacheTimeout="86400" />
      </providers>
    </roleManager>
  </system.web>
</configuration>

It worked after removing the "DataProtectionConfigurationProvider" entry from config file.The problem was that I was using the config file from different computer and the key was stored in the computer from which the config file was take.