RNS E issue...

[WayneCS3]

i need some help, if i unlock my car and sit in it without turning the ignition on ,every 5 mins or so the headunit does a light crack noise through the speakers and a faint black line appears across the nav screen even thoe its not on then fades away.. what is this and how can i fix it?.

its a RNSE from my 2007 S3.


Thanks