Hey!
I had the same problem all of you do, with L2 crashing apon launch when using Windows 8. I did some digging on the forums, and Ignis posted a link to some DLL files that fix the problem.
Lineage II works perfectly on Windows 8, once you copy the DLL's found here (**link removed since is not needed anymore**) to your Lineage II system folder. (the link was posted by Ignis him/herself).