I'm having this same problem with some DVD's.
I put it in, it sits there for about 10 to 15 seconds like it's trying to read the disc, then it just stops. when I try to see the disc, it's as if there isn't any in there.
These are newer DVD's as well. Had it happen with the Scorpion King, Annapolis, and Treasure Planet, so far that I can recall.
They play fine on the stand-alone DVD player, but won't read on my PC. I have a Sony DRU510-A player, if that's any help.
Do these newer DVD's snoop your registry before they display? I notice my HDD light goes on the whole time it's trying to access the DVD. Maybe this is just normal, but I have to wonder if it's snooping my registry and deciding it doesn't like something I might have installed and refuses to be viewed...