Microsoft .NET framework 3.5 installation had failed on sql server 2008 x86 installation in windows 7 x64 ultimate

Hi

I am using Windows 7 x64 Ultimate OS.

I already Install .NET Framework 3.5.

i try Install SQL Server 2008 x86, but Setup file Not opened.

Error msg Raised

Microsoft .NET Framework 3.5 installation has failed.

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

How ti fix this issue.

how to install SQL Server 2008 x86 in Windows 7 x64 Ultimate?