PhotoShop CC Will not Load At All

Press Ctrl + Alt when you launch Photoshop. A dialog box should appear to select a different scratch disk, where you can choose the H drive.

Hello,

the presence of an older version does not interfere with the installation. It might give you that message if you are using both version and you are running out of RAM.

I think Tony is absolutely on spot as to where to go looking for the issue. 

Normally I clean up my laptop, that has a very limited budget in ram and gives me the scratch disk full message more often than not when I work on Bridge. Many things depend on the capacity of the computer we are using. I notice that, while cleaning the scratch disk opens to more space, it does not save me from the application eventually filling it up again.

As a general advice, try not to have too many applications open and running at the same time.

Have you set H: as your first scratch disk or have you seen the menu when loading PS not at all?

Do you start Photoshop as Administrator (right click on PS Icon > Properties > Compatibility > Run this program as an administrator)?

If this doesn't work, you can run "Disk Cleanup" to get more extra space on C:

https://support.microsoft.com/en-us/help/4026616/windows-10-disk-cleanup