Getting dvd to play

[Linda]

I finally got around to installing a dvd player. I followed the 
instructions for Resticted Formats Playing DVD someone posted for me 
last week, but I get an error message from Totem Movie Player that it 
can not read from resource.
If I try to play a commercial dvd  from VLC  I get  a title page showing 
the movies title with a choice to play movie and some other things but 
in about 1 second it disappears and I have the choice to push play pause 
etc across the top and a blank white box. If I push play it repeats 
title then blank screen

At this point I can play a home movie dvd with Totem or VLC although it 
does give me a green stripe across the bottom of the frame.

Can anyone give me any suggestions on how to get the commercial dvds to 
play?

In your opinion which program is the best choice for playing DVD there 
are quite a few of them?
                            Thanks
                             Linda