After installing Community get There is a duplicate scriptResourceHandler section defined
[Edit]
After installing Community get the error message 'There is a duplicate 'system.web.extensions/scripting/scriptResourceHandler' section defined.
this is because the installer adds this section but it already exists in .NET 4.0 framework.
Solution
Switch the application pool to use .NET 2.0
EPiServer version
'CMS 6'