TFS, subst, Visual Studio 2010, relative paths

My TFS workspace is at C:\Users\...\MyProject, which I have mapped to X:\ using Windows subst command. In my Visual Studio 2010 solutions, this works fine for most of the projects. Only 2 of them are always linked (absolutely!) wo the C:\Users\... path, no matter what I do.

I tried:

1. Removing and re-adding them, obviou开发者_如何学Pythonsly.
2. Removing the explicit absolute mapping for those 2 projects in my workspace settings. It is re-created as soon as I add the projects.
3. Manually twiddling in the solution file with Notepad. Makes the source control binding invalid, and 2.'s explicit bindings are re-created when I rebind them.

Some help would be very cool. I'm stuck for several hours only dealing with source control...

Cheers Matthias

P.S. Some might wonder why I do the subststuff: As the project directory names are pretty long, the often exceed 260 characters, which makes many features in the VS/.NET environment stop working.