DVD player tries to load and displays unknown disc

For your enjoyment.
APEX DIGITAL DVD AD-1110WM

The disc spins slow and then fast and sounds like a stripped gear while is erractically searching on the disc. After one minute, unknown disc is displayed. I am using a DVD-R and I burned programs from Green Planet channel. I looked at the laser lens with a lupe and gently use a micro cloth to remove some accumilated fibers...some looked like fibers from clothing that floated by wind current into the unit. All else seems good.