title: keras examples doesn't work
body: <p>I am trying to study Keras library and I tried to run this example from <a href="https://github.com/fchollet/keras/tree/master/examples" rel="nofollow">https://github.com/fchollet/keras/tree/master/examples</a></p>
  
  <pre><code>'''Trains a simple deep NN on the MNIST dataset.
  Gets to 98.40% test accuracy after 20 epochs
  (there is *a lot* of margin for parameter tuning).
  2 seconds per epoch on a K520 GPU.
  '''
  
  from __future__ import print_function
  import numpy as np
  np.random.seed(1337)  # for reproducibility
  
  from keras.datasets import mnist
  from keras.models import Sequential
  from keras.layers.core import Dense, Dropout, Activation
  from keras.optimizers import SGD, Adam, RMSprop
  from keras.utils import np_utils
  
  
  batch_size = 128
  nb_classes = 10
  nb_epoch = 20
  
  # the data, shuffled and split between train and test sets
  (X_train, y_train), (X_test, y_test) = mnist.load_data()
  
  X_train = X_train.reshape(60000, 784)
  X_test = X_test.reshape(10000, 784)
  X_train = X_train.astype('float32')
  X_test = X_test.astype('float32')
  X_train /= 255
  X_test /= 255
  print(X_train.shape[0], 'train samples')
  print(X_test.shape[0], 'test samples')
  
  # convert class vectors to binary class matrices
  Y_train = np_utils.to_categorical(y_train, nb_classes)
  Y_test = np_utils.to_categorical(y_test, nb_classes)
  
  model = Sequential()
  model.add(Dense(512, input_shape=(784,)))
  model.add(Activation('relu'))
  model.add(Dropout(0.2))
  model.add(Dense(512))
  model.add(Activation('relu'))
  model.add(Dropout(0.2))
  model.add(Dense(10))
  model.add(Activation('softmax'))
  
  model.summary()
  
  model.compile(loss='categorical_crossentropy',
                optimizer=RMSprop(),
                metrics=['accuracy'])
  
  history = model.fit(X_train, Y_train,
                      batch_size=batch_size, nb_epoch=nb_epoch,
                      verbose=1, validation_data=(X_test, Y_test))
  score = model.evaluate(X_test, Y_test, verbose=0)
  print('Test score:', score[0])
  print('Test accuracy:', score[1])
  </code></pre>
  
  <p>and than I got this error
  <a href="https://docs.google.com/document/d/1bo24LXbfK-NzqOBmblqM5KL91P3L3FMD1Wzq-Z5VMq0/edit?usp=sharing" rel="nofollow">https://docs.google.com/document/d/1bo24LXbfK-NzqOBmblqM5KL91P3L3FMD1Wzq-Z5VMq0/edit?usp=sharing</a></p>
  
  <p>I'm running windows 10 64bit with amd gpu, python 3.5 and keras in the latest version</p>