[Help] What is this error?

Can anyone help me out? =]
What kind of format should it be?
Code:
Code:
System.BadImageFormatException: An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B)
   at NewestCOServer.Native.BF_set_key(IntPtr _key, Int32 len, Byte[] data)
   at NewestCOServer.Main.Blowfish.SetKey(Byte[] data) in C:\Documents and Settings\Administrator\Desktop\rikardo updated\Main\Blowfish.cs:line 85
   at NewestCOServer.Main.GameCrypto..ctor(Byte[] key) in C:\Documents and Settings\Administrator\Desktop\rikardo updated\Main\Blowfish.cs:line 15
   at NewestCOServer.Main.GameClient..ctor(Boolean Robot) in C:\Documents and Settings\Administrator\Desktop\rikardo updated\Main\GameClient.cs:line 51
System.NullReferenceException: Object reference not set to an instance of an object.
   at NewestCOServer.Main.GameWorker.ConnectionHandler(StateObj S) in C:\Documents and Settings\Administrator\Desktop\rikardo updated\Main\GameWorker.cs:line 33