SPI - Apparently Random pulses on CS/SS line
See my page about SPI.


  Pin 10 of the Arduino is the SS line - so does this mean you have to use it for the peripheral SS line? Or should it be kept high? The answer (from the Atmega documentation) is that the SS line (pin 10) must be configured as an output (regardless of what value is on it). If configured as an output the Arduino ignores the value on that line, and thus the SPI hardware will not be put into slave mode.
  
  Since the value on pin 10 is ignored, providing it is set as an output, then it can also be used as the SS line for your first, or only, slave. You could then use other pins (eg. 5, 6, 7, 8, 9) to control other slaves.


For you to successfully make an SPI master then pin 10 on your Uno must be configured as an output, regardless of whether or not you actually use pin 10 for SS. Under the circumstances, you may as well use pin 10 for SS if you are going to make it an output anyway.




  This issue persists when using pin 10 as the SS.


I tried your code with my Uno (no device connected) and had no such problems. Sounds like an electrical issue to me.