2500A Does not recognize a DVD

Hi,
I just put in a new NEC2500A drive. However, it does not seem to recognize certain DVDs. These DVDs play fine on my ESA DVD player, and are also recognized on my Samsung DVD-ROM drive and I/O Magic (I dont know what rebadged drive) DVD+/-RW drive in my other computer. The DVD seems to be loading, and then, nothing happens. If I open D: in MyComputer, it’s blank. This is turning out to be a huge annoyance. Does anyone know what the issue could be. These are not burnt DVDs.
If I have to use DVDInfoPro, what kind of info should I be looking for? Any help would be greatly appreciated.
Thanks.
-K-