Problems with sound in dvd with Asus

Hello,
I am recently experiencing problems with sound when i try to watch a dvd in my Asus. I have always watched movies with my laptop, but 2 weeks ago I have started to watch one of those movie downloaded(was not the first time) and the dvd start to speed very bad making an horrible noise and the computer got stucked, since then the sound when i insert dvd is very bad, either with proper dvd, not downloaded. I don't have problems with audio cd, the sound is fine. I have installed the dvd driver again, but hte problem is still there. what can i do?what is the problem?