Software like Norton Antivirus, Zone Alarm, Panda (and other firewall, security and antivirus software) can reject access to internet. Please, make sure that antivirus programs allow AB Bulk Mailer to connect the Internet via 25/587/465, otherwise it will not be able to send mail. It is also strongly recommended to disable checking outgoing emails in these programs.
Pay attention that the sending speed may vary. It depends on your Internet connection speed and the size of the message.