If it goes on white then goes off about 5 seconds later then you need to make sure that...
1.You do not have some anti virus program blocking it. If so you need to make flyff an exception to it.
2.You are running the right launcher and have a fully updated launcher.
3. You need to make sure that when you open neuz.ini (Little paper with gear) that when you scroll down to where it says IP: "" make sure that it has IP: "giolog.ath.cx"
EDIT: Almost forgot, I once had this problem on another server and when none of those were working I re downloaded dataSub1.res and put it into my flyff folder. (You replace the new one with the old one) Just type dataSub1.res in google and the first link is a download from mediafire.
