If you are using Vivado on a Windows development machine, you need to be aware that Vivado can produce random errors if the Windows path name length gets too long. It is critical that you keep the base path name short for your Vivado projects. You can see references to these issues on the Xilinx Answers database:
http://www.xilinx.com/support/answers/52787.htm
http://www.xilinx.com/support/answers/55481.htm
If you are having build problems and the error message seems to make no sense, try reducing your path length.
Bryan
