After Effects Mask is cropping down resolution I have two videos, from one I create a mask.

In preview I have output fine.

Preview:


In RAM preview and render queue, output is weird:


I am a beginner ,using After Effects CS6 trial.

I have followed several masks tutorials, not a single tutorial has addressed this issue. I am using no effects at all, there are only 2 videos.
Set the RAM preview resolution to full.