Question: I have a Visual Studio 2010 solution with a few projects. I can successfully build with Build -> Build Solution or Build -> Build MyCompany.MyProduct.MyProject. After building I press CTRL+F5 and successfully run the start up project. This works as expected.

After I change a source file, save it and then again build (with either Build -> Build Solution or Build -> Build MyCompany.MyProduct.MyProject) it builds successfully. I am still able to press CTRL+F5 and run the startup project. This again works as expected.

The problem is in the following scenario:
After I change a source file, save it and directly press CTRL+F5 then Visual Studio 2010 says BUILD FAILED and there are no errors. And it doesn't start my startup project (of course).

Am I missing something?

Answer: 
Seems a bit late, but what worked for me was to check my Output window.

I had a reference to a Function that didn't exist yet. I don't know why it never came up in the Error List, but the Output window told me exactly where the problem was.
Some times if the Directory path is more than 248 chars it will fail the Solution.
Make sure complete path is less than that.I have faced the same issue than i made short and it did worked for me.

Regards
Venkateshwarlu,
MSBI Developer,
Hyderabad.