You MUST have version 3.5 or better of the Microsoft .NET framework installed on your computer. If you are using Windows 7 or better and have kept up to date on your Windows updates, you should already be set. Users of Windows XP/Vista won't have a new enough version of the framework unless it was installed manually in the past. The easiest way to obtain it is via the optional downloads section of Windows update. Select the latest and greatest version of the .NET framework, install it, and then run Windows update again looking for important / critical updates pertaining to the framework. Install those too.