RESOLUTION 1:
Reset user interface settings by renaming Desktops.xml file:
1. Close Toad.
2. Rename the Desktops.xml file to Desktops.old, by default this file is located in the "C:\Program Files\Quest Software\Toad for Oracle\User Files" directory.
3. Launch Toad and a new Desktops.xml will be created.
User interface settings will return to default and the error message should no longer be received.
RESOLUTION2:
Reinstall Toad by performing a custom uninstall and remove all files to remove Desktops.xml. Refer to Solution 12846 - "How to completely uninstall and reinstall Toad for Oracle", for detailed steps on performing a Custom Uninstall:
https://support.quest.com/SUPPORT/index?page=solution&id=SOL12846After performing the Custom Uninstall, delete the Toad installation directory, by default :\Program Files\Quest Software\Toad for Oracle, to ensure that all corrupted files have been removed.