Saving a script via Editor window results in non-readable SQL or TXT file. File shows graphical characters.
1. Select View | Toad Options menu option
2. Drill down to File | General section
3. Uncheck "Save source file in Unix format" checkbox and hit OK
Another similar issue to refer to:
SOL92664 Toad editor inserts hidden characters at beginning of text files and can cause the script to fail.