Okay. That sounds like you are accessing a bad update server. You need to get your computer to switch to another one.
You can do this by restarting the computer, but there is an easier way: If you have Windows XP, click the Start button on lower left, then click the "Run.." option. It brings up a window. Type
ipconfig/flush dns
and hit your enter key. You will get a message "dns sucessfully flushed" Then type
exit
and hit the enter key. This will switch to another update server. Try to enter the game again. You may need to do this a few times until you dont get the "connection to the update server has been terminated message.'
Okay. You got a good connection to the update server. This is a different problem. NCsoft has reset all the passwords. Your password will not work until you go to PlayNC main site and first change your master password (Using 'Lost Password' option) and then change your Lineage II password on the PlayNC site (also using 'Lost Password' option.) The info is here. (http://boards.lineage2.com/showflat.php?Cat=0&Number=666784&an=announce&page= 0#Post666784)