Recently I took a class where the instructor could not get one of his DVDs to play for the class. This particular DVD was a custom compilation made by his organization. The error I saw when trying it on my laptop was that it was blocky and played fast. Another person tried it and got a black screen.
I search Google on "free DVD codecs" and found a codec to that worked.
Once installed, it still did not play with my default player, but it did play with the player installed with the codec -- the Media Player Classic.
Because this first codec worked, I did not try the other downloads. I tried this one first because the file size was the smallest. So if you find that you still have trouble, try one of the other links within the first result (Codec Pack All in 1 or K-Lite Mega Codec).