uninstall game AND delete it from regedit

then re install it all and maybe it'll work

if u dunno how to delete the key on regedit, go in windows start button => run ... => write "regedit", then in here click on HKEY_LOCAL_MACHINE => click on software => webzen folder, delete it then now u can reinstall game and let's see if it works, thats what i purpose you to do, thats what i would do if i got the same problem

gl dude, wishing i gave u the solution