What could be the problem?

I've been burning with a sony dvd+r rw discs. using dvd shrink and nero combination. We use 2 cyberhome dvd players the 30.00 type i believe. When i put it in one player it doesn't play at all and in the second one it will play but then it will skip and freeze. I burnt movies a along time and not sure what the problem is with this. Could it possibly be the player, discs or the combo i've been using. Thanks in advance