When I try to load a solution, I get the following error:

> 
> The project file [filepath] cannot be opened. The project type is not supported by this installation.
> 
> 
> 

After hitting OK twice, my solution loads fine except for the two test projects (the [filepath] above references these two test projects), which are greyed out. When I try to expand them, they show the message:

> 
> The project file cannot be loaded.
> 
> 
> 

I am running VS08 Pro SP1 and .NET 3.5 SP1. The test projects were also created in Pro. There are two weird components to this problem:

1. When attempting to "repair" the VS installation, it says that tests are already installed. This is evident by the "Test" option in the menubar at the top of VS.
2. If I wanted to create a new test project, VS gives me the option at the creation dialog.

I have seen [this question](https://stackoverflow.com/questions/1295791/visual-studio-2008-project-wont-load-but-no-errors) and tried implementing the answer via the VS command line prompt but no dice.

Does anyone know what the heck is going on here?