map is not shown when I select Places in iPhoto

On latest version of snow leopard and iphoto.

Not sure when this started happening but it used to work and now it doesnt.

I open iPhoto, select Places and then select the globe symbol at bottom of screen and I jkust get grey screen.

If I select i it tells me I have 2734 photos. Events, photos and faces all work fine

Any suggestions on how to get my world map back showing all pins for all my photos