Do you see the player in System Profiler?
Yes but it's greyed out. It will let me open it but nothing happens from there.
Will it play CDs?
Yes it's playing a non-commercially produced CD right now.
Does it read non-comercially produced DVDs?
No. You can hear it attempt to spool up and load but it doesn't get that far. It tries twice before it ejects itself. That is the same thing it does with commercial DVDs.
CDs and DVDs use different laser settings, hence the different performance.
Have you tried cleaning the superdrive with a standard lens cleaner that uses tiny brushes?
Also, a SMC reset can sometimes cure the problem:
Resetting the SMC (System Management Controller) on Intel-based Macs:
Resetting your Mac's PRAM and NVRAM: