I know this question is marked as answered but I found that the script is looking for the port as a LIKE instead of looking for the exact port as Rob pointed out. So port 13344 was open on my box and the script would fail.
To fix problem Edit the startup.bat file and change this line:
CALL :IsPortTaken %port%
(which is line 23)
to this
CALL :IsPortTaken port%
This will look for ports that start with 3344 but may still fail if you have port 3344x open
this would be best
CALL :IsPortTaken port
Since open ports are exact this would be the best option
Hope this helps
Ray