Ok a few idea's to try are..
Corrupted install.
Can you delete your game folder and re download? all over.
Update your video card drivers.
With the 'other' servers you've been testing have you had to install any 3rd party programs?
Go into the option.ini file in your linage 2/system directory and open it in notepad, have a look at the graphic settings and try setting some back to fasle to see if that makes a difference.
Memory, after having some very weird for no reason at all, crashes in Liinage, i decided to seperate my memory sticks so instead of operating in dual mode, they now oprate in single channel mode and i have not had any weird crashes since. So could be memory, or even virtual memory. (but if its a memory glitch you should still see some error)
The only time i would get a fast d/c from the game was when the server went 'sigturn' those times. Are you sure a GM is not kicking you?, have you been a norti Dent?