Have Tryed an GameGuard Emulator ( That emulate your GameGuard in Local) ?
If not, Search On my posts..I have Posted It some days Ago.
If you have Tryed it..then Dunno what I can say :s
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Append on Apr 7 2007, 01:08<hr> Here My Post !
How to bypass Gameguard...
1)Download this => GameGuardEmulator
2)Open your hosts file with notepad [x:/windows/system32/drivers/etc/hosts (x = the name of your hard disk that windows are loaded)] and add this at the end
127.0.0.1 localhost
127.0.0.1 l2testauthd.lineage2.com
127.0.0.1 l2authd.lineage2.com
127.0.0.1 nprotect.lineage2.com
3)Extract the GameGuardEmulator and open "startapache.bat" now run lineage2
4)Gameguard bypassed!!
GameguardEmulator : --> here the link

have a fun !