You need to fix your user privileges/ file permissions. That error occurs when your user does not have permission to write to temp folders. It doesn't appear with other programs because they don't function this way.
+1 to Mylenium's assessment.
It might be helpful if you would go into Photoshop, click the Help - System Info menu, copy the info, and post it here (redact the serial number info if you like). It's possible experts here will be able to see a configuration or installation issue in the detailed info there and offer you more specific restorative suggestions.
Thanks for the Answer,
You mean the standard temp folder of Windows 8? or what does Photoshop use?
And to Noel Carboni:
I would really like to do that, but as a matter of fact, I am not able to start photoshop....
Try pressing and holding the Control and Alt keys when starting Photoshop. Get the keys down immediately upon double-clicking the shortcut. That should give you a dialog where you can select a scratch drive.
Yes that works, I get the dialog!
BUT, Now I can choose between "Startvolume" and "C:"
neither is working....
Somehow you do not have permissions to access the folders on your own system.
That it's Photoshop's scratch area that's implicated hints to me that you should check to make sure you have Full Control permissions for your TEMP area and all files and subfolders within.
Did you go through any kind of out-of-the-ordinary setup on your system?
Good Point! Thank You so very much! It works now!!!
The problem seems to be Adobe Acrobat Reader:
I made a new partition D: and changed the temp folder to D:Temp.
Now it works perfectly fine!
There is STILL a problem with Adobe Reader XI changing permissions on windows user temp file. Just got me. Oct 27, 2015