I see used the same article you did when exporting projects from FCP 7 to compressor. However, I do it a little differently. I highlight the entire time line and then in sequence setting I choose apple pro res 422. I do this early on and edit in pro res. Then I export from there as a self contained QT file. Follow the steps in compressor.
Then I use this for DVD SP:
http://www.kenstone.net/fcp_homepage/autoplay_in_dvdsp_stone.html.
You might be doing all this. Sometimes DVDs are duds and don't play well on other players. Make sure you are using high quality blanks. I have no idea why anyone would want to play an HD project in SD. DVDs also load slower during a showing so I don't get it.
If this fails you might want to take your project and burn the DVD on a different computer.
MacPro4,1 2.66GHz 8 core 12gigs of ram. GPU: Nvidia Geoforce GT120 with Vram 512. OS X 10.6.x; Camcorders: Panasonic AG-HPX170, Sony Z7U, Canon HV30/40, Sony vx2000/PD170; FCP 6 certified; write professionally for a variety of media; teach video production in L.A.
