I am having I think the same problem.
I work at a small TV station & use DVD architect on a daily basis.
I use Architect to have all of my credits & commercial blocks for a show ready at the dvd player (live shows). On one show & one show only when I burn the DVD it loses the thumbnail (keeps the title) of each clip & each clip has no video. After I burn the disk & reload the project it comes up with a cannot render error on the clips.
I thought maybe my project had become corrupted & started from scratch & it still did it! All the clips are standard ntsc avi files, they span 4 menus with 6 to 9 clips per menu.
Again, I use DVD Architect (& Vegas) on a daily basis & I am only having problems with this one show…
I am currently copying the directory to a flash disk to move it to another computer and see if it is computer specific. BTW, new quad 4 computer running 64 bit Windows 7.
Did you fid a fix?