Every now and then when I build my solution here (with 7 projects in it) I get the dreaded \'Command copy exited with code 4\' error, in Visual Studio 2010 Premium ed.
I had the same problem. However, nothing worked for me. I solved the issue by adding
exit 0
to my code. The problem was that while I was doing copying of the files, sometimes the last file could not be found, and the bat returned a non-zero value.