If Babis's solution doesn't work try this; Go to user accounts and click on create new account.Type a name in the box,but don't use the same name as the administrator account you already have,you can change it to "Michael" later. Click on next and put a dot next to "computer administrator",then click on create account. Now delete the original administrator account,and then rename your newly created admin account by following Drews instructions in his earlier post. Hope that helps.