Argh, the same thing is happening to me now. Could you elaborate a little bit on your post Vashiel? I have vista and am a bit confused at what you mean.
Edit: I figured out what you mean by type into box, but typing /ipconfig flushdns seems to do nothing.
you can just press enter once the update window opens up, or you can just run the game by your l2.exe in your system folder.. I replaced my desktop shortcut with that one anyway.
I get the same thing every once in a while too, it says "The connection to the update server has been terminated" and I have to open it again and try to start the game before the launcher can connect to the update server.
what i did (since I have a back up copy of L2 and a PTS copy of L2 as well as the game play copy of L2 on my pc) is I clicked on the PTS updater *wich went thru* then clicked the backup copys updater in the backup copy then clicked the normal L2 starter and it fixed itself.
PS i think i confused it jsut as I probably confused 50% of the people reading this thread :P
anyway in simpler terms I have 3 copys of L2 one being the pts, I jsut went though and clicked the updater in all of them and it fixed the error.
I got the "click the start button REALLY quick" solution going now, but rebooting and dns flush etc all didn't fix the real problem. Opened a support ticket, but with the advice to quick-click I am going again...
just create a shortcut from your "C:\Program Files\Lineage II\system" folder and find l2.exe
You'll have to run the original LineageII.exe from the main l2 folder every once in a while to update your client, but it shouldn't be giving you the termination msg every time I think. Just wait for support to hopefully help a bit
Start, accessories (right click Command Prompt) click copy, paste shortcut to desktop, right click on command prompt and click run as admin, THEN type /ipconfig flushdns