Photoshop(Beta) v.26.7 on IMac V15.4.1. Every photo on opening has grid lines over picture.

I must have turned on some aspect in Photoshop Beta recently but every photo opened in it has grid lines over the entire photo.  I have searched for a reason but have not found a way to remove these overlying grid lines.  

I have removed the version and then reinstalled but this did not change anything.  This is quite anoying and would like to eliminate the problem

Any suggestions are welcome.

Thank you in advance,

Bob Keller