I have a setup and deployment project that, on our build server, reports the following in the summary:
========== Rebuild All: 25 succeeded, 2 failed,
yeah, I've had this before.
Not sure about your set up, but try this is appropriate:
Firstly, right-click on your Solution file > Properties > Configuration
In there, use the build tick boxes to experiment with which projects build together, and which don't.
Also, in your file system, delete the debug/release folders for all of your projects.
Finally, in my experience, this error is usually caused by a corrupt/missing web.config.
let me know how you go