SL2 Slides Go White and Fill with a Big Red X

Hey there.

I get to see the red cross as well, which is pretty frustrating with a deadline in my neck. I submitted a support request (00515659 ), but if anybody else on here has some good advice, I'll be glad to read it. 

I started a new project, copied some text out of MS Word into SL2.

Sometimes when I click on a textfield and meanwhile everytime when I click 'justify' to format the text, I get to see the red cross, as described and shown in this entry:
https://community.articulate.com/discussions/articulate-storyline/sl2-big-red-x-suddenly-appears-in-slide-area
(The text format doesn't change in the end)

I am using a Mac with Parallels to run SL2. Didn't have any problems for month until now.

The work arounds some users and staff recommended (like close & open, open in a new file) don't work. Reinstallation didn't make it any better.