It looks like you're running the 32-bit version of Visual Build. The 32-bit Windows "System32" folder as seen from a 64-bit app (64-bit Explorer, Cmd, etc.) is C:\Windows\SysWOW64. Copy psexec.exe to that folder from a 64-bit app to make it available to 32-bit applications. See here for more details:
http://en.wikipedia.org/wiki/WoW64