You seem to have a unique combination of factors, any one may be part of the problem. I can only give a generalized set of recommendations for this.
First, DVD players are rather dim devices. Not much in the way of 'brains' in them (keeping the cost low) so they are easily confused. The newer models are getting smarter, but still nothing like a what a PC thinks with.
Things that will confuse some players - 8 cm disks. Stick with the standard 13 cm size.
Use DVD-R since that was the first recordable DVD media and most players understand them. Only the very oldest DVD players will get confused.
Put the JPG and any other PC oriented data in it's own folder, don't put it in the VIDEO_TS folder. That's reserved for only very speciific files and anything else may confuse even the newest players.
Include an AUDIO_TS folder, even though there's nothing to put in it. Some older players are rather stupid about it and won't recognize the DVD as valid unless it's there.
Reserve a folder on your PC for just the exact files and folders you'll be burning with Nero. This will let Nero burn everything at once. Tell Nero that you're making a DVD-Video. Then cross your fingers.
I like to burn at a slower rate than the maximum my drive can handle, that helps compensate for media quality variances and burner aging (lasers don't last forever).
Fav quote - "Experience is whatcha don't get 'till ya don't need it no more."
System - Athlon 1.4GHz, Win98, Hauppauge PVR250 receiver and compressor.
Software -Magix Movie Edit Pro 10, Nero 6 + NeroVision Express, Moho 4.61, PSP 8.1, Bryce, Quicktime 6.52 pro, Goldwave 5, DVD-Lab.
Cameras - Panasonic GS9, Canon ES8400V, Canon EOS D20 and Canon A70