I had the same problem today, while I was upgrading some VC6 project to VC2012.
In my case, it was because some of the operation in Custom Built Steps failed. In project properties, go to Custom Build Step, you can see there maybe some something in command line edit box. Open a windows prompt and paste the command to it. Run, check if there is something wrong and fix it.
If there is no command line in the project property Custom Built Step, maybe you should check properties of every single file of the project.
If the command line has some macro, replace it with an actual value.
Or you can echo the command in VS output window:
cd %(somedir)%
echo %(somedir)%
You won't miss it this way.