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: 
I closed my visual studio. 

Deleted every bin folder. (I had a weird permission error, so I deleted the files and back track deleted the folders including bin). 

Reopened visual studio. Performed build or rebuild and everything was working again.
I had the same problem, solved by the following step

go to Tool->option->projects and Solution->General, make sure to check the box "Always show Error List if build finishes with errors", in this case, visual studio will show the error list.