Recently I've noticed that every time I try to use a command like "mkdir", I get "permission denied" when used without "sudo". I guess that's because I am not connected as an admin, only as far as I am concerned (and the System Preferences "Accounts" window) I am.
This happens only after certain time that I do not use the computer.
Any idea why this could happen?
EDIT: The problem happens only with a specific folder, which is used by MAMP PRO. MAMP has its own settings page for the permissions, but when I change owner control to admin, PHP uploads doesn't work. When I change it to _www, everything related to this folder requires authentication.