Are you rendering interlaced ??
Because if you do so, and you watch them on a PC monitor ( which is progressiv) it got these lines in there. You can change that in the render settings. Chose Field Render -> Off. Than it should work.
If your problem is more complicated than I’m sorry.
Tim
“If you look up idiot in the dictionary know what you find ?”
“A picture of me ?”
“No! The definition of the word idiot”