Error building VC7.1 project

[rod]

Help! I am running into an error when building a .NET project which states:

Illegal characters in path.

The path that I am setting it to is a vcproj project that as far as I can tell is valid. I can cut the project path out of the build step and paste it into explorer and the project opens fine. The project also successfully builds in VS .NET (2003).

Funny thing is if I replace the vcproj with the solution name the step executes fine....what am I missing?