rosserial arduino: tf::broadcaster contradicts using publisher

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Hello together,

I am running rosserial on the arduino UNO with the "rosserial_server" packages node "serial_node" under ubuntu 14.04. The setup works in general, I just can not solve the following problem:

When using a tf::broadcaster and another publisherof arbitrary type at the same time, the arduino must run into some error. At least the serial_node either never gets anything back from the arduino or gives the error output:

[WARN] [WallTime: 1422869167.806875] Serial Port read returned short (expected 1 bytes, received 0 instead). [WARN] [WallTime: 1422869167.807257] Serial Port read failure:

I prepared a minimal example:

#include <ros.h>
#include <std_msgs/Int32.h>
#include <ros/time.h>
#include <tf/tf.h>
#include <math.h>
#include <tf/transform_broadcaster.h>

// Configuration hardware
const long BAUD_RATE = 115200;
int PUBLISH_HZ =10;

//time of last tf send
long int lastSendMillis=0;


//ros variables
const char base_link[] = "/base_link";
const char odom[] = "/odom";
ros::NodeHandle nh;
geometry_msgs::TransformStamped t;
tf::TransformBroadcaster broadcaster;

//std_msgs::Int32 iMsg;
//ros::Publisher intChatter("timeDifs", &iMsg);

void setup()
{
  t.header.frame_id = base_link;
  t.child_frame_id = odom;

  nh.getHardware()->setBaud(BAUD_RATE);
  nh.initNode();

  broadcaster.init(nh);

 // nh.advertise(intChatter);
}

void loop() {

  int timeDiff=(millis() - lastSendMillis);
  if (timeDiff >= 1000/PUBLISH_HZ) {
    // send it now!
    lastSendMillis=millis();

   t.transform.translation.x = 1;
   t.transform.translation.y = 1;
   t.transform.rotation = tf::createQuaternionFromYaw(M_PI / 2.);
   t.header.stamp = nh.now();

   broadcaster.sendTransform(t);

  // iMsg.data=timeDiff;
  // intChatter.publish(&iMsg);

   nh.spinOnce();
  }
}

It is enough to comment in the message definition "std_msgs::Int32 iMsg;" to produce the error. I can not see how this is related.