[MacDV] DVDs only work on some computers: please help

[elizabeth cromwell]

I finished making my first iMovie (iMovie 5.0.2) handed off to iDVD and 
burned a DVD. I tested the DVD on my desktop computer (Mac dual G4, 
OSX10.4.6, on which I had created it) and on my laptop (Mac G4 PB, 
OSX10.3.9); it worked great in both places. I then took the DVD to work and 
it wouldn't work on ANY of the Macs there (tried 4 or 5 different computers 
running both OSX 10.4 and 10.3) nor will it play on my home TV/DVD player. 
The same DVD still works fine on my desktop and laptop computers. Help! What 
am I doing wrong?

Tried the following with no luck:
Using a different brand of DVDs
Using DVD-RW and DVD-R
Creating a disk image from iDVD and using Toast instead of iDVD to burn
Slowing down the burn speed to 1x
Using both "Best Quality" and "Best Performance" encoder settings
Video standard is set to NTSC

Should I re-export to iDVD from iMovie? Any help/ideas greatly appreciated.

Frustrated new user in Seattle