Can't install SQL 08 on a Sever 08 box

[Jonny Wright]

I am running Server 08 with Visual Studio 08 installed. When I try to install SQL 08 (Dev Edition) I get the error message;

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Microsoft SQL Server 2008 Setup

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Microsoft .NET Framework 3.5 installation has failed.

SQL Server 2008 Setup requires .NET Framework 3.5 to be installed.

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OK

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I do have .Net 3.5 installed. I have even gone as far as installing Vis Stud 10 Beta (which ships with .Net 4.0 Beta) but still getting the same error. Anyone else have any ideas/had this same problem?

Thanks