Why will a DVD play in one DVD player but not the other?

[Merchise]

I just bought the spider man 2Disk DVD, and the first disk "the move" works fine in my PS2 DVD player, but the 2nd disk "bonus features" will not play. It just says Please insert a PSX or PS2 format disk. But the disk works fine in my Phillips dvd701 player. Just the opposite is true for my Gundam Wing DVD It won't work in my Phillips DVD player, but will play just fine in my ps2 and my friends dvd player.

Any thoughts would be great.

Merchise

[Merchise]

So, if nobody knows what is going on with my dvd's, could someone give me a good website or point me in the rite direction to get some help.

Thanks,
Merchise