6
log in as admin, and then type this in your browser
http://www.yoursite.com/modules/system/admin.php?fct=groups
Then go to webmasters group and give yourself system admin rights by putting a checkmark in the boxes. This happens by clicking "update" in the webmasters group without checkmarks in the system admin rights.
On initial install you have system admin rights, but the webmasters group defaults to having no checkmarks in the boxes, and when you manually click on "update", your rights are taken away, common occurance..