Hi,
I had a same problem with it . i have nissan primera 1.2 2002 model.
But now imy problem is gone. 
What i did, 
1st: disconnect the battery for 5 minutes. & then reattached it. 
2nd: opened whole front of dvd, cd & satnav. including whole control panel. 
3rd: ditchadded all the connection from the panel & also taken off all wires of dvd, satnav & cd. 
4th: I have not taken or move the screen. 
5th: after that I have reattched all the cables back & fixed the unit & I have decided that I will go to bye the whole new system. 
6th: & finally, when i started my car, the whole system was working in good manner. I wasmuch surprised.
If you have a real proble, then it's worth triying this thing. I got my banifit. 
If you ghave quary, please contact me at cmpatel23@gmail.com
                
 chirag patel
                
 January 2008