I just tried your batch file, and it works fine for me. The cmd window
closes. I'm on Windows XP, so maybe it is different on Win7.
A possible fix may the to change the start line into
START "C:\Program Files\PTC\Creo 2.0\Parametric\bin\parametric.exe"
That way the program is started in a new window, and your batch file
continues with the next statement instantly instead of waiting for the
program to start.
Another possible solution is to use a shortcut instead of your batch
file, since all you seem to be doing is changing startup directory and
starting Creo. You can set the startup dir in your shortcut properties.