I had the same problem. I used vi -b [filename]vi -b [filename] to see the added characters. I found the control characters ^@^@ and ^M^M. Then in vi type :1,$s/^@//g:1,$s/^@//g to remove the ^@^@ characters. Repeat this command for ^M^M. WARNING
Warning: To get the "blue" control characters press [Ctrl+v]Ctrl+v then [Ctrl+M]Ctrl+M or [Ctrl+@]Ctrl+@. SaveThen save and exit vi.