First, let me start by saying that you should avoid opening multiple treads with the same question, because it is not convenient for anyone (the Support team, the community nor for you).
Now, moving to the issue. If you move from .NET 2 to .NET 4.0 you will have to download and use the DLL files for .NET 4.0 instead, because the old DLLs are not compatible with .NET 4.0.
If there are any other issues that you are facing, please provide some more details on them.
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