No that was a pretty straight forward explanation -- now I cannot tell you exactly what is happening per-sae but I can tell you what it sounds like to me -- the python/pyqt platform that the interpreted python/pyqt code runs on is some how getting applied to your initial call but then when you make that outside call to another *.py file (?? which I do not understand why your are doing that without having imported it into your main program) that is not getting brought properly onto the python/pyqt platform -- possibly because its not designed to do that or if it is will probably require something special to do so -- now if you are running from within (or upon) the python/pyqt platform (via say a terminal emulator and having typed the "python" command) and you start your program from there yes it may work because everything you call will be placed upon that platform automatically
Still this brings us back to that question -- why are you accessing exterior *.py files from within a *.py program instead of importing that *.py file and then referencing the code within that file?
Still this brings us back to that question -- why are you accessing exterior *.py files from within a *.py program instead of importing that *.py file and then referencing the code within that file?