Problem with client

[cuka]

I first used client version 1.25 and server revision 647.
Client and server are on the same machine.

The problem is client get's stuck in logging in and then it throws an error:
java.io.utfdataformatexception: malformer input around byte 137.

Then I used client version 1.81, same server revision, both client and server on the same machine.
The client complained with:

The server responded with an invalid server key.

I tried with the server in linux, other machine, and the client doesn't even "see" the server.

I'll be glad if anyone could help me.

Thanks