I moved your question to a new thread as the thread you attached it to was unrelated and had been answered.
For your issue :
1.Are you able to use File - New and create a new document from scratch and see it - just use the brush and see if you paint?
2. What kind of file are you trying to open?
3. What settings do you have in Preferences - Performance - Graphics Processor Settings?
It happens for new and opening files. The 'work space' flickers between black and white and I can not use any of the tools.
My graphic processor is as follows on a Mini Mac (which is new):
'Use Graphic Processor' is checked on.
First try setting the GPU to off. Restart Photoshop and see if that helps
If it does, switch it back on again but then go to "Advanced Settings " and try each of the three drawing modes in turn (Basic/Normal/Advanced) restarting Photoshop after each.
It worked...now I am trying the different levels in the advanced sittings.
Just checked the other settings and I will have to leave the GPU off for it to work.
Thanks so much!
I'm glad you got past the initial problem, however it would be good to get the GPU working as some parts of Photoshop such as Liquify and 3D need the GPU to work.
I' m not sure if you can update video drivers on the MAC - perhaps a MAC user can advise here (I use Windows).
Also , if you get some time, you could try re-enabling Basic - but disabling specific features in the checkbox below.