me too had same problem and result was that server at your isp identifies your IP address only along with your MAC address, one thing you can do is use old NIC or just phone your ISP to register your new MAC address with your IP address. That will solve the problem.
Any body here knows how to configure cyberoam client for suse linux 9.1 as i have posted abt it earlier but no success and i can only access net with win xp box. I'm using client supplied by cyberoam website(24 hr online). Thanx