Ok, your problem ist either you have written the dvd with a wrong program.
For the best result burn on a dvd-r DL, i use verbatim dvd´s and they work exellent, be sure to have - dvd´s not plus.
What you can try is a full factory reset, it works mast times, if not than try to do a rewrite of your dvd.
What i also find out is that your laser unit has to be cleaned, i had the same problem with a friends avic, afther cleaning the laser it worked well.
a complete factory reset works like this ;
Remove disk
Hold reset and eject
Release reset but hold eject
Screen will go back in and out-then says please press the reset button ... don't
Then with joy pad press...
up,right,up,right,down,right,down,right…then ok (joypad button inwards)
Password screen will come on screen breifly
Test mode screen apears - click joystick to right once
Scroll down to number 6 - program forced write (ok)
Find number 1 system program (insert disk --cndv 40/50/60?)
Press 1 system program (ok)
Select 2 dvd/cd rom (ok)
Select language… (english)
Press (view –pos) button
Should see system program going up in %
When finished press (back)
Find number 6 program forced write again (ok)
Number 3 application program (ok)
Select 2 dvd/cd rom (ok)
Select 1 uk english...then press (view – pos) button
Should see system going up in %
When finished press (back)
Test mode page 1
Select 6 - clear back up memory (ok)
Should say finished then asks for reset button to be pressed
Press reset on front of unit
Start sat nav again
Askes for language press no (read text)
System starts
Buttons
Ok = joypad inward
Back = joypad to the left ... note this will bring you back to previous page
Back = band button ... note this will take you back to the main menu