Thanks for the reply,
I have ArcGis desktop 10.0 I am not sure which version the map packages I
am trying to open were made with, but the only one I could open is the one
I uploaded my self which is in version 10.0.
One of the ones I couldn't open is the U.S. counties layer, the first map u
see when you go to add data online through arcmap.
Asaf