Need help with software bug

Okay so I reinstalled xp the other day, and now when I burn a dvd in nero I get
skips and freezes. It happened when I first installed nero 6, when I originially bought it. I did something and fixed it, but cant remember what it was. I think it was when I updated it, I know it isnt the burner. I just bought a Sony 810a, and it does it on both the sony, and I also have a nec 3500a. I know it isnt the media because I havent switched. Since I started having this problem, I bought some ty media and some verbatium mcc 004. It does it on all of the media.
I use dvd fab if it is disney protected, and then dvd shrink. I dont get the skips and freezes when watching it from the hard drive. Both drives are in external enclosures, one on firewire and one on usb. So it isnt the interfaces. All I can think of is Nero.

Any Help will be appreciated. Thanks Nick