I have a sony dvd rw aw-q170a in a dell dimension 4600. It was freezing when I tried to load any disc. So, I adjusted thing in the bios. So, that the hard drive boots before the dvd drive and that the dvd drive is set to auto. That helped it not to freeze, but it still won't read dvd's. It will load cd's and play them, but it is very choppy playing music from the disc. Any suggestions on how to fix this problem?