Chances are your physical Com ports are 1 & 2. Your modem will install its own port(apparantly 3). Not being able to re-connect would lead me to beleive that when you are disconnected port 3 is being left open, this will stop your modem from being able to communicate. A re-boot will reset all ports. If you re-boot and your modem can't communicate how do you ever get a connection?