FatalExecutionEngineError appears after changing my app to x64

I have a project with two app and i need to launch it with x64.

So i change the two app to x64, but FatalExecutionEngineError exception appears on this line:

 public void GetStatus(out SERVERSTATUS serverStatus)
    {
        try
        {
             ifServer.GetStatus(out serverStatus);
        }
        catch (Exception)
        {            
            throw;
        }
    }

this the complete exception :

Managed Debugging Assistant 'FatalExecutionEngineError' has detected a problem in 'C:\Users\BeanAirTunisiaTeam\Documents\Visual Studio 2013\Projects\opc_client\OPC Client\BeanairOPCClientCodeSampleC#\BeanairOPCClientCodeSampleC#\DirectOPCClient\bin\x64\Debug\OPCClient.vshost.exe'. Additional information: The runtime has encountered a fatal error. The address of the error was at 0x490394a6, on thread 0x2c28. The error code is 0xc0000005. This error may be a bug in the CLR or in the unsafe or non-verifiable portions of user code. Common sources of this bug include user marshaling errors for COM-interop or PInvoke, which may corrupt the stack.

Update:

ifServer is an interface,

this is the code of the methode GetStatus():

void GetStatus(
    [Out, MarshalAs(UnmanagedType.LPStruct) ]   out SERVERSTATUS    ppServerStatus );