I've been writing DVDs from a computer at my college. At first, from iMovie it started skipping upon playback; but played fine in the lab where I burned it. It skips on my Mac, DVD players, and PS2s. If I use Toast, it really screws up; the sound is constantly falling out of sync and the video still skips. Again, the DVD plays perfectly in the lab I made it.
I slowed down the write speed for the Toast DVD, it didn't seem to help.