Cannot play DVD

Hi,

I can't find a way to play DVDs on my MacBook Air. The DVDs work fine on a normal TV DVD player but I have now bought and tried 2 different USB external drives and neither of them work on my Mac.

Odd because I am trying to watch a box set, and season 7 plays absolutely fine but seasons 4 and 5 don't work at all (haven't tried any other seasons). I can see the files on the disc and my laptop recognises that there is a disc there, but when trying to open the files on VLC, vGuru player, or the laptop's own DVD player the screen is just black and the DVD player gets very loud and hot.

The only thing I can find about it is that the season 4 and 5 DVDs are universal disc format - but I'm not sure if this is a reason they are not playing?

I've been trying different combinations and solutions for a week so would appreciate any help!

Cheers