s320cdi ignition/gearbox sensor

[weldman1969]

hi,i have an s 320cdi (03/53)62k.when i switch on the ignition everything lights up as normal the heater plug goes out i turn the key and nothing! I have noticed that when this happens it doesnt show on the lcd what gear or comfort/sports mode it is in but it shows the date.i have sometimes heard like a clicking/small clunk noise in the ignition,and sometimes when you turn the ignition when it shows you are in park the display shows it in reverse,when i switch off the ignition and turn it back on it all dissapears again and will not start.Also when i am in reverse mode the reverse lights flash on and off as i am reversing could this be a gear box sensor fault?the gearbox itself is fine when started the tiptronic works fine in either sport or comfort mode.thanks for your help regards ian