Sorry, i have no answer for you but another question. I've had similar probs with Win32. Especially when dealing with pre-existing Apache. I ended up finding the pid of the apache process (with ps.exe) and killing that process from perl. I had to know the name of the application though in order to kill it. Sounds like you do, so try to kill it. Which leads to a more direct question. Can you map a port owner's pid? Or...
Is there a way to detect which process is binding the port you want?

jtrue