The Anonymous Monk above probably has it right: the wperl executable is itself marked as a GUI program, so does not get a console window, but when you run tasklist in qx``, you are running a child process from an executable that is probably marked as a CLI program, so the window appears. It has been a long time since I did development on Windows, but that API call will probably solve your problem, if it actually does what the name implies — always an iffy proposition on Windows.