Strange Colours covering my image in Lightroom

[Bernadette]

Lightroom is covering some of my images with weird colours.  Do you know why this is happening?

Thanks

[Damien Symonds]

Hi @Bernadette, it could be a number of things.

First, could you do this for me?  https://www.damiensymonds.net/thread1.html

[Bernadette]

I have a Mac desktop running MacOS High Sierra and Lightroom CC. It is over 4 years old, and has 32 GBGB of RAM. Its hard drive has 3.12TBGB free out of 2.5 TBGB. The last time I shut down was more than a week ago, because I'm an idiot. I have never run a cleanup program.

[Damien Symonds]

Yes.  Yes you are.