InDesign black beams

[BernhardFrei]

Hey guys, I have a question.

I´m currently working on a book and all of the sudden these black beams start to appear and just like they appeared, they disappear all of the sudden.

Sometimes it´s a header, sometimes it´s a whole paragraph and somehow I couldn´t find anyone who had the same problem before me.

Can somebody help me to fully get rid of these?

Thanks in advance!

[SJRiegel]

Is there a pattern to when this happens? It looks like what would happen if your preference (Under Display Performance in the Preferences Panel) for  Greek Text Below ___pt is being applied when the file view is smaller.

[BernhardFrei]

I couldn´t detect a pattern until now. Sometimes i delete an empty line and all of the paragraphs with the same format turn black.

Where can I find the display performance actually?

Thanks for helping!

[SJRiegel]

It's in the InDesign Menu 

InDesign > Preferences > Display Performance. 
If this is only happening with one document, it could be corruption in that document. In that case, export the file as IDML - this can sometimes clear minor file corruption.