Removing the AsyncTask and using a traditional Thread instead of combining it with runOnUiThread seems to work. But I still have not found the reason why the AsyncTask is so "unstable".
Here is the code that works for me:
public class ImageActivity extends Activity {
private Thread worker;
public void onCreate(Bundle bundle) {
super.onCreate(bundle);
setContentView(R.layout.main);
worker = new Thread(new Runnable(){
private void updateUI(final List
