Well, skipping version checking is not enough. But it's a good start.
Look at tlogin's cshandler.cpp, and search for something like wVersion.
By the way you have to fix the annoying bugs like 0/0, system error. Which bugs are all server sided. It's not hard to fix it. Just find out why you are having a system error.
Basically, some bastard or an automated function sends packets to your server. And activates a dword. I don't want to give out my info, but ... look at tchartable, what's weird when you having a system error :)