or maybe y Mistaken did y turn Off ur router ?
after the router turn ON the PS3 will sign in y Automatically to Network
if y select ( Sign in me Automatically ) when y start ur PS3
Did it say you signed in or another user signed in with your account? If it said you signed in it's because the auto log in just completed. If it said another user signed in then you need to change passwords again. Do you have more than one PS3 with your account on it?