Hmm, that's interesting.
May I assume it happens every time the frame appears? The little cropped CG-like image I mean.
If so then I guess I know what is broken but I don't know exactly why...
Edited:
So, first of all, thanks for the report. It turned out to be quite important information.
In short, the problem seems to be with one of the plugins for renpy I'm using. It's bugged for SOME systems and I was totally unaware of that. I looked it up, and it looks like the author has confirmed the issue and fixed it in the new version. I'll just update the pluggin and it should be good in the future.
Again, thanks for letting me know!