"Server Error in '/' Application" when trying to open Website. Website will not load and Event (4368504)

The website will not load and displays: Server Error in '/' Application. Runtime Error.
Additionally the following error is logged in the event log:

Source: ASP.NET 2.0.50727.0
Event ID: 1310
Task Category: Web Event
Level: Warning
Event code: 3008
Event message: A configuration error has occurred.

Exception type: HttpException
Exception message: Could not load file or assembly 'System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' or one of its dependencies. The system cannot find the file specified. (C:\Program Files (x86)\Quest Software\ArchiveManager\Website\web.config line 41)

IIS cannot locate .NET 3.5

Install .NET 3.5 on the IIS server

If the IIS server is Server 2008 R2, .NET 3.5 is a windows feature and can be installed with the following powershell command:

import-module servermanager; get-windowsfeature net-framework

For all other versions please download .NET 3.5 from Microsoft: http://www.microsoft.com/downloads/en/details.aspx?FamilyID=ab99342f-5d1a-413d-8319-81da479ab0d7&displaylang=en