Those shortcut keys need to be set by the XL Toolbox every time Excel starts. So if you press this key sequence and the message appears, that’s proof that the XL Toolbox is running on your system.
The most radical way to stop this is to uninstall the XL Toolbox from the system.
Alternatively, go to the
COM Add-ins dialog (not the ‘normal’ add-ins!) and see if the Toolbox appears there.
If the Toolbox is running and you can see the menu (‘ribbon’), then you can adjust the keyboard settings here:
Let me know if this helps or not.