This is a frustrating and annoying bug which happens to you at home in your DVD player or CD player. The good old dust spoils the party. When you get into your car and start her up you will see NAVI displaying the following greeting "Error Reading Disc". Even after swapping for a known good DVD disc the system will still show the same message. I have had this error once and fixed it by buying a CD lens cleaning disc with soft fibre bristles,I didn’t opt for the nylon bristles disc as it would be too abrasive. Initially the protruding bristles do pose a challenge in getting the CD into the front of the dvd. if you try the bristle at 90 degrees to the mouth it goes in cleanly. Run the process 3-4 times and you will find fine dust trapped on the bristles, some owners have taken the entire unit out to clean the lens with lint free swaps dipped in IPA (Isopropyl Alcohol). Owners who don’t get the desired effect with the CD are suggested to go for the IPA wipe as the next step.