slow motion; pixels mixing and

Hello everyone !
I have a few questions about making a slow motion in After Effects. Is it posible to make a big slow motion in After Effects with 25 fps file in ? I try everyhing : time remaping in AE, Twixtor and so on but i didnt get a good results. Always when i want make big slow motion e.g. 20%, 10% or something like that, strange thing was going on, the view was distorted and pixels were mixing up with some move on the screen etc.
Do You have some ideas ?

Thanks ! r4inski