Hi,
If you have manually configured users and buttons, you must comment the last #exec line, the error you get for voicemail.conf is because of the script that is executed in that line, that you most probably do not need nor want to execute.
Regarding the port, you most probably have FOP1 running and binding to that port, or FOP2 that is already running. You can only have one daemon binding to a specific tcp port at any time. So, if you have FOP1, stop it and then start FOP2. If you have FOP2 already running, you do not need to start it again (or you need to kill the running one if you want to restart).
You can tell the daemon that is taking the port with the command
netstat -lnp | grep 4445
If you see as process name "perl", it is the old FOP1, if you see fop2_server , then it is fop2.
Best regards,