Im wondering if it is something to to with the fact that the hearer files include the SPI library,
Where in SPI.h or any other header included from there is SPICS defined? I cannot find it.
Whcih makes me thing that it uses part of the SPI and Arduino.H library to carry out all of the CS functions?
No, it doesn't.
Did you set the pin as an output in setup()?
pinMode(5, OUTPUT);
digitalWrite(5, HIGH); // disable first
Edit: changed to code tags to remove smiley display and added initial HIGH.