I'm not able to reply your answer.
Have you tried clearing, resetting and restoring File > Info's own
Click the Preferences button at the bottom of the File Info dialog box.
Yes I cleared the preferences.
Adobe Photoshop X64 CS5.1 Prefs
But this button I can't find any more in the german version!
I'm no longer able to write the metadata. The windows is blind or
blocked as not completly started.
See the attachments!
Thanks for help
At this point you can try a clean uninstall and reinstall of Photoshop. If something is damaged, the re-install would replace it. Please remember to check the "erase or delete personal settings" when you run the the uninstall.