IOW you can't save at all, whether PSD or anything else - the save dialog just doesn't come up?
Could the dialog be off screen for some reason - for instance if you have disconnected an external display?
Can you try with a file you don't mind overwritten, make some changes and then just hit Ctrl + S - does that save correctly?
Thanks for responding. I can't save at all. The dialog box doesn't come up. So I can click on FILE > SAVE AS but then nothing happens. I have checked if it is off screen. It is so weird to just start happening and randomly. I have tried what you suggested before, but sometimes it won't let me save and then other times, saves as normal. I can't work it out but it is very annoying as I lose work!
What about ctrl + S? That will just overwrite the file without any dialog coming up. If that works, it's the dialog and not the save procedure itself.
Long shot, maybe it's video card related. Try to disable "use graphics processor" for a while and see if it happens again.
Windows or Mac?
Thank you. Ctrl S doesn't work either but I will try disabling the video card. Thanks for the tip