Enabling Code First Entity Framework VS Web Express 2012

I've run into this issue twice now. Both times I've had to uninstall entity framework then re-install it for each project in the solution. One thing that took me a while to figure out the second time I did this is that I had to re-start Visual Studio (2012) after re-installing Entity Framework (or I continued to get the "Could not load file or assembly '[path]\packages\EntityFramework.5 .0.0\tools\EntityFramework.PowerShell.Utility.dll'" error).

To get to the Package Manager Console go to: Tools -> Library Package Manager -> Package Manager Console

In the Package Manager uninstall Entity Framework for each project (I selected each project from the Default Project dropdown at the top of the Package Manager Console):
Uninstall-Package EntityFramework -Force

Then install it for each project:
Install-Package EntityFramework

At this point attempting to run the Enable-Migrations command gave the error still, until I closed and restarted Visual Studio. Then it was successful, as was the Update-Database command (after setting AutomaticMigrationsEnabled to true in the Migrations.Configuration file).

Had the same issue on two different machines while using projects on a network drive. This answer fixed it for me.