Cannot edit SSIS Script Task in Visual Studio .NET 2008

[Database Administrator]

I have an SSIS package created in Visual Studio .NET 2008 which contains a
Script Task. When I open the Script Task Editor and click on the 'Edit
Script' button. I get the following error message. When I check the GAC I
have version 8.0.0.0 of the missing file but not 9.0.0.0.

On the same PC I have the developer edition of SQL Server 2008 installed
with the Integration Services option.

Thanks.

TITLE: Microsoft Visual Studio
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Cannot show Visual Studio 2008 Tools for Applications editor.

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ADDITIONAL INFORMATION:

Could not load file or assembly 'VSTADTEProvider.Interop, Version=9.0.0.0,
Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies.
The system cannot find the file specified.
(Microsoft.SqlServer.VSTAScriptingLib)

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BUTTONS:

OK
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TomM