Not sure if this is a the right topic as the question is sort of on 2 things but will ask anyway.

Ive recently changed from making vcds to svcds when i make them for my own pc to play them they work great, but when i make them for a friend they do not play on his dvd player (Phillips 723) they come up all blockey and pixilated. But when he makes them himself using all the same programs (smart ripper, dvd2avi and tmpgenc) they seem to play great in his system.
Does anybody know why this happens?
Do different systems give different svcd/vcd results?
Could different writers have different results?
Or does he have a crappy dvd player.

Any help would be great as this is driving me mad.

Cheers.