DVDs go through 3 stages:
1) Detect the disk (yours passes this one)
2) Attempt to read the TOC (Table of Contents) from the disk (Yours is failing this one!)
3) Read the disk to completion… (Yours never gets this far)
In your case, you are stuck on step 2. I would start with an attempt to clean the lens on the optics assembly. Use a cotton swab and alcohol and GENTLY clean the surface of the lens. Be careful as the lens is supported by fine wires that allow for focus.
Report your results here.
Dan