How to delete custom keys?

In the Settings --> Customize --> Keys menu, when I select a custom key the Delete option is greyed out. How then, do I delete an existing custom key? (or is my installation corrupted?). on Windows XP/SP2.

Regards, AB

The Customize - Keys tab displays all hotkeys assigned directly in the Customize dialog, as well as those assigned in any toolbar which you currently have open. The hotkey assignment that you cannot delete is most likely assigned inside of a toolbar button, not directly in the Keys list.

Check the value in the Type column, if it says Toolbar, it is defined inside of a button somewhere.