I have a Hitachi DVD-Rom 7500 drive installed in my computer. Before I had computer issues, the drive worked fine, and I played all of my DVD-movies on it before I bought a standalone DVD player. Then I had to reformat my computer, and now when I play DVDs in this drive, they play, but the audio and video are choppy. It's not the disc itself, because it happens on every single disc, and they work fine in my DVD player. What's going on here? Thanks for any help.