Major problem playing dvd's

[Richard]

I have install kdemultimedia and mplayer and vlc player,
even kaffeine can't play standard dvd's

I get this error message:
The source seems encrypted, and can't be read. 
Your DVD is probably crypted. According to your country laws, you can or can't 
use libdvdcss to be able to read this disc. (Media stream 
scrambled/encrypted)

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Have a standard dvd rw burner in my laptop.
that can burn dvd's cd-r and play music cd's.

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Please this is very frustrating not be able to play movie dvd's

Thanks in advance.
Rich