Vista - DVD probem/Pixelated video/sound ok

I am running Vista Home Premium. Not 100% sure, it came preloaded with Dell. I am playing a DVD, "Dexter" by Showtime. the screen breaks up displaying multi-colours intermingled with the movie. The sound is OK. I rented two movies. The first movie played fine (StepBrothers-Will Ferrell-funny). I put in the second movie, (Dexter/ by Showtime). The second movie plays, and the sound is working fine, but once the picture comes on, the screen breaks up displaying mulitple colors and lines. It's like how the screen breaks up on my digital tv, when a storm is coming in and it looses its signal, without the audio garble though. I have a Dell desktop, Inspiron 531, 2G. Any suggestions? Thanks

Could be the DVD itself. A damaged disc will sometimes do what you are saying on any device, or the disc is encoded in such a way that the dvd drive cannot decode it properly.

Check the disc for scratches, even small ones. If there is, please go to where you rented the dvds and let them know about the problems with the disc.

If the disc is not scratched, then try it in a dvd player or something else that will play dvds to see if it works.

Yes I agree.

Firstly look at the DVD to see wether it has obvious damages.
Secondly try it in a stand-alone DVD player (if available)
Thirdly look at your playback software.

Most issues with video/dvd playback on computers have nothing at all to do with broken/malfunctioning/insufficient hardware or disk damages.

There is a lot of high-quality (FREE) video playback software out there you might want to check out.

Here's a list of my favourite programs in order of quality:

1. Media Player Classic
If you get this all your playback issues are a thing of the past.
This program is very small, lightweight, doesn't even require any installation and will play back ANY, and I do mean ANY multimedia file/disk.
It also has GREAT configurability options for the power user. It lets you set parameters for any and all codecs used and even lets you select which codecs to use. Oh also, it is COMPLETELY FREE!

2. Zoom Player
This program used to be my first choice because it offers almost the same configurability and playback as MPC but its major feature was that it looked just a bit more polished and the playlist was a lot more managable but it got kicked down to 2nd place because apparently it doesn't like vista all that much. I often get floating point errors trying to play certain containers/streams (I think its OGG) and that put me off immensly. Oh almost forgot! the reason it's called ZOOM player is because you can SEAMLESSLY zoom videos in and out during playback!
There are some free versions of this program out there but they are either oudated or pirated so if you want the best functionality out of it you WILL have to buy it.
I haven't personally bought it nor do I intend to seeing as MPC provides me with everything I need and more.

3. VideoLan VLC Media Player
A lot of people swear by this program, and I used to be one of them
The reason I don't use it anymore is that it doesn't allow external codecs.. playback support isn't all that great and video quality is downright poor (no processing codecs to smooth up the video making it look more soft and less pixelated) but the thing that did me in with this player was its POOR 5.1 audio support. Basically it 'has' built in SPDIF (digital I/O) support via a codec but I just can't get it to work.

And there you have it!
I hope you find this of use.

PS.
A noteworthy mention to PowerDVD.
If you are looking for professional state-of-the-art failsafe proper disk (be it DVD, Blue-ray or even HD-DVD) playback then Cyberlink PowerDVD is the way to go!