Event crop in Sony Vegas creates a strange effect

[Srivas]

Hi!
Im editing one video in Sony Vegas 7 and Im facing one strange problem. The thing is that when I crop the event, then after rendering mpg file for DVDA, motion starts to appear wavy in DVDA preview screen and also on my PAL TV. Why is that? Is there anything to do to avoid it? I tried different rendering options, still the same problem occurs.

I added a picture to make my point clear.

Any ideas? :thanks:

[Adub]

it's best if you upload you pic to an external image hosting site like photobucket or imageshack.

Also, make sure you have no effects affecting (huh) you final output.