I know you don't want to hear this, but maybe you should "just" rebuild your slideshows in iMovie or iPhoto or even iDVD. It's very easy in both and you have tons of control easily available; cropping, Ken Burns effect, straightening, music placement, various cross fades, etc.
I've never used Roxio tools for making slideshows, so I can't really help with that. Hopefully someone here can.
BTW, have you tried simply burning your project to a disk image? You could then mount the image and use DVD Player to play it just like any DVD. If the image works, burn it to disk. Otherwise trash it and make changes before trying again.