Error when changing an applications Target Framework from 2.0 to 4.0

I've had a problem with Crystal Reports when changing an applications Target Framework from 2.0 to 4.0 

Error:
Could not load file or assembly 'file:///C:\Program Files (x86)\SAP BusinessObjects\Crystal Reports for .NET Framework 4.0\Common\SAP BusinessObjects Enterprise XI 4.0\win32_x86\dotnet1\crdb_adoplus.dll' or one of its dependencies. The system cannot find the file specified.

Resolution:
Add the following to app.config:

<startup useLegacyV2RuntimeActivationPolicy="true">
<supportedRuntime Version="v4.0" sku=".NETFramework, Version=v4.0" />
startup>

System: VS 2010, Crystal Reports 13, Windows 7 x64