sat/nav no power light?

Hi I have a BMW E46 on a 2001 plate. It has the Built in BMW SATNAV system, the disc loads it cycles as if it is trying to read it, then after about 20secs it ejects the disc, the entire time the unit power light remains off?
Also on the display in the car the SATNAV icon does not appear? Any ideas, in actual fact the SATNAV unit is made by Phillips.