It could be server is down for maintenance, but you should still be able to log in.. Have you checked to make sure your password & log in name is correct? Try sending Tech support a msg.
same thing happened to me
for some reason i dcced and couldnt get into the game or the forums
i figured the server went down but when i logged in clanners said it didnt
minuets after i logged so did 2 bot trains so obviously some ppl were effected by something
There were some login issues earlier today but those should be resolved now. Please contact Technical Support (http://support.lineage2.com) if you are still unable to log in. Thanks!