First of all, if you don't know much about how applications work inside of the OS, its wise to not look in the application folder(s). Deleting anything here can make your apps go haywire. If this happened, then you are best to 1)unregister photoshop, 2) uninstall your entire suite. 3) reinstall the suite and finally 4) reregister photoshop.
All images/textures/photo's including dng, cr2 and nef files need to be stored in your pictures folder and no where else, unless you're an intermediate user on your OS. In your pictures folder you can create folders for organizing the pictures whether by location, season's, time, or file format.
Then when you back up you can just drag a copy of the files to another drive including cd's or dvd's.
This will make sure you don't accidently delete important app files.
All this said, my OS of choice is Windows, so if anything does not sound right, thats why.
Hopefully this helps...
Thanks for your suggestions - did reinstall and that helped a bit but
not all problems solved, but can at last open thumbnails in Photoshop
Do you have at least 10-20% free space on you harddrive?
Have you reset you preferences, or at least trashed the cache?
Yes and yes - tearing hair out!
I am inserting a related problem. I have CS3 installed on an iMac running OS 10.4.11
Bridge stopped working. Everytime I launched it and tried to select a source for images, it froze. Consequently, I uninstalled CS3 and then reinstalled it. I didn't get an installation of Bridge...just CS3.
What do I have to do to get Bridge back?