The fact that the message is being spoken means that one of the tool windows
was not closed properly.  Could you try opening and closing all the tool
windows with the keystrokes assigned to them.

ALT+CONTROL+K opens/closes the keypad window.
ALT+CONTROL+P opens/closes the properties window.
ALT+CONTROL+Y opens/closes the playback window.
ALT+CONTROL+M opens/closes the mixer window.
ALT+CONTROL+N opens/closes the navigator window.
ALT+CONTROL+R opens/closes the parts window.
ALT+CONTROL+V opens/closes the video window.

Try pressing each keystroke a few times.  Don't be surprised if the first
press doesn't do anything, it sometimes takes a second for Sibelius to wake
up with these keystrokes.

item.  Just to clarify:
F6 speaks the position of the selected item.
CONTROL+F6 speaks the position of the playback line.
P starts playback from the position of the selected item.
SPACE starts playback from where it last stopped.
CONTROL+SPACE rewinds to where playback last started from and plays from
that point.

Press AltF2.  A dialog containing all the system items appears.  Select the
item you want and press enter.  You will land on the item.  Press ENTER
again to edit the item.  Press escape when you're done editing and the item