Final render differs from Video Sequence Editor

Hey there,

I am working with Blender for the first time and I am trying to simply cut a video with the Video Sequence Editor. As I need to combine scenes shot with a GoPro and a screen capturing, I tried to arrange them as picture-in-picture. This looks perfectly fine when checking it in the Video Sequence Editor. But when I render the whole video using the “Animation”-button, the resulting video is totally different than the one I checked in the VSE. The screen capture-sequence is way faster in the rendered video than it is in the VSE, although the GoPro shot with 29fps as well as the screen capturing software (CamStudio) and Blender is supposed to render with 29fps as well.

Could anyone give me a hint on what mistake I made?

Thank you very much in advance, this problem already freaked me out!