Metin2 HackShield unknown_error (errorCode 100)

Hey Epvpers ^__^

I have a question.
I'm playing with some friends a p-server called Acuria2 .
Today my cousin downloaded it too and tried to start it ;o .
He said he gets an error like : Metin2 HackShield unknown_error(errorCode 100)
Could you guys please help us ?! ;D
Tnks ;3

Yes i have the same problem with my client at the biginn it worked fine but now I have the problem