Distorted image after rotating it

The following problem occurs…

For this I use only one frame;
I’ve imported an image (jpg) in Flash and I’ve placed this image in a MC. I used AS to rotate the MC (_root.myMC._rotation=30;). Works perfectly. The image looks just fine.

But when I ad a second frame in front of this frame (purpose: preloader), the image gets distorted. This also happens when I use a second scene.

So it only seems to works when I stick to only one frame.

Does anyone know a solution for this problem.