Handbreak conversion

Hi again,
I am currently converting lots of dvds i recorded via a panasonic dvd recorder through Handbreak. I choose the preset for ipad. I de-flag "large file" and I choose videofilters - deinterlace - fast if I see a noise in the preview.

I use a pc sony vaio... do not kill me... currently thinking to swith to a mac (mac mini).

My question is: if I use these preset but use them for iphone 4 I can smoothly watch the video with windows media player or media player classic or vlc.

Problem is when I choose iPad. Sometimes it works, but sometimes the screen appears with noises or all green with the above mentioned programs. But if I watch the video via itunes or quicktime no problem....

Do you have any idea where it can depend from?


Many thanx

Andrew