Winavi crop my video files

I have a few rmvb files which i want to convert to mpeg2 with winavi, but lately i dont know why, it used to work prefectly fine. but now after converting and i burn to dvd with nero, i get two side stripe on both left n right of the screen. it is not nero’s problem as i try converting n burning mpeg2 files to dvd using files i converted before winavi had problems and it worked fine. i have tried different versions of winavi as well and have no luck. i suspect its the codec matter but i have already installed all its require like Klite codec pack.
please wat is my problem? how come my video got crop, well it didnt get crop just the picture became smaller. i have tried changing the settings on winavi but doesnt work

You can try this:go to menu,you can find “option”,click it,then find this"use winavi built-in decoder”,don’t seleck it.Then do what you want again.
If it still that,i think you may need to email to support@winavi.com,they will help you.
good luck
And also you can try to play the converted file to see if it ok,then burn.