Help! Burned discs have crazy video...

OK I'm getting frantic...Altho my project plays perfectly in the dvdsp 2 simulator and the size is 110 minutes 3.4 gb, the first 1/4 of the dvd plays ok but after that things fall apart. The video starts to breakup into hundreds of little rectangles revealing pieces of video (and audio) from other parts of the dvd and even video that's not even ON this dvd (but are elsewhere in other FCP projects)!! What's also weird is that different parts of this burn are OK or screwed up vs. a previous burn. I've never had this problem before. I used 2 pass vbr best, a target of 3.7 and a max 5.9 and AC3. This is a system with 3 external Lacie drives that've never let me down before. As I said previously the DVDSP2 simulator plays perfectly. I've repaired permissions several times with no improvement. This is on a G4 titanium laptop with superdrive running OS 10.2.8. and FCP 4. Is the drive shot? Help!
Mac Type: (G4, Ti laptop)
Proc Speed (1.0 GHz)
L2 cache size 256
L3 cache size: 1 MB
DSP version (2.05)
OS: (10.2.8)
QT player 6.5.2

You are experiencing what is essentially - dropped frames on playback. although not really dropped frames as in the editing process; the frames are not being reconstructed properly upon playback.

I would generally say that you encoded the video at too high a bit rate, but the 2 pass 3.4 - 5.9 and AC3 audio seems very reasonable.

Are you using DVD Studio Pro to burn a DVD or some other way? Your description seems to imply that the first 1/4 of the DVD playout is working but after that it pixelates. You are watching this on a set top DVD player - are you not?

Thanks-- i actually solved it this morning. In prefs/destinations i had set the destinations to nearly identical projects and so the video_TS had files scattered all over the place. I'm guessing my laptop's burner had trouble pulling them all together. Both my laptop and consumer players crapped out playing the dvd. it's fine now...