HI Leo
A few other things to try - just do the build in DVDSP, then drag the VIDEO_TS folder this creates into Toast and try this as your master disc ( make sure your delete the .layout and .lay files from the VIDEO_TS folder, these are just for DVDSP and could cause probs in a set top player).
If the disc still won't autoplay, try creating a track with 2 sec of black and make that your First Play, then end jump that to your root menu.
What you're describing seems quite unusual - I've not had this problem with any disc I've created.
Hope this helps
Cheers
B