Problem with converting DVD to S-VCD Mpeg2 480x576

My problem is that when I convert certain DVD’s to S-VCD 480x576 Mpeg2, there are lots of thin horizontal black lines across the video footage that are very noticeable. These lines are very similar to the ones that you see when you zoom in on dv footage captured from a dv camcorder.

I use Smart Ripper, and have just tried Clad DVD-Net 3.4.0 to rip the DVD.
I then use DVDX 2.2 for the conversion process.

Is there something that I should set up in one of the pieces of software to stop this from happing?

Some movies are fine with the default setting, but there are a lot of settings in these three pieces of software to manually set up.

One last thing, I have used DVD Pro to convert the dvd’s with this problem, this dose seem to rectify the problem but the resolution is only 384x288 thus making it very grainy.

Any ideas anyone?

Please help

Cheers

Neo