Tom, I deactivated RS Head Cleaner Plus plugin and galleries worked in Chrome and IE. Menu appeared as well. But my Google page speed is down to the red zone again. (( Guess, I will have to figure something out. I wonder if WP Minify plugin works with GP without issues or not? Thank you for your help anyway! It is so cool to get it practically immediately. It would have been a pity to lose such a good theme.
PS: A sidetopic. Is there a way to make borders (both outside and between cells) in tables (in posts I mean) visible in your theme?