Roles and permissions

I've upgrade my moodle installation from 1.6.3 to 1.7.1 with the last distribution and when i connect to my moodle site as admin. Moodle recognize me as an Administrator in the Profile Page but I can't access to the admintration task because it says to me that i don't have Permission to access admin site.

Thanks for your help

Loutcholycos