You get this output when MonkeyRunner can not find the .py file that you want to run.
DONT forget to add the absolute path of your .py file so that MonkeyRunner knows where to find it. If you dont add the absolute path, MonkeyRunner looks for that file only in the same folder that MonkeyRunner itself resides.
EDIT: You can copy and paste the following into the arguments field of Eclipse External Run Configurations. It will pop-up a window so that you can select what file to run. It makes life easier!
${file_prompt:"Choose a File":${resource_loc}}