A couple of weeks ago, we ran a Silverlight course using Visual Studio 2010. At some point, you had to create an entity framework model. Several students had an issue where the template for creating a new Entity Framework Model was not present. In some cases it was present, but when they selected it to add the item, they got an error.
The resolution: run devenv /setup. You would typically open a VS2010 command prompt and run it from there.