Unable to add new contact or a new group even though both are on the toolbar

I used to be able to add both a new contact or a create a new group by clicking on "Contacts" button. I still can open the contacts folder and "New Contact" and "New Contact Group" are in the toolbar; but when I try to open either of them, nothing happens.

I am able to add a new contact to one of my existing groups.

My operating system is Vista Home Basic and the email program is Windows Mail. I would say my computer skills and knowledge are beyond beginner; but not advanced.