cmd.exe does not support UNC paths, which the path you launch it from is.
Thus it changes its path to the windows directory, but ofcourse the files it needs to combine are not present there so it will return with an error stating that it cannot find the files.
What i suggest is that you copy the planeshift files and run_me_first.bat to a directory on your drive (not your desktop) like C:\\planeshift and try running the batch file again. See if that helps.