Default shortcut for adding a comment in Writer is Ctrl+Alt+C,
but in Polish programmer keyboard layout it results with letter "Ć".
It's standard keyboard layout used in Poland.
version 3.5.0 on Windows with US keyboard and Dutch key-definition produces © when pressing Ctrl-Alt-C and no comment is inserted.
I think this shortcut is not ideal for Windows O/S.
(have changed the summary as the bug is not confined to Polish keyboard settings)
*** This bug has been marked as a duplicate of bug 36588 ***