Instead of messing with the cable just go to the PSN menu -> Account management, triangle -> Sign out :)

That's where the auto sign-in option is as well, in case you'd rather be offline by default and online only when you tell it so.

i have a question that is similar to this i guess.... i noticed that when i get messages itll say "received a message" or whatever, but in the top right bar with the clock and friends online, theres NEVER a logo that shows i have unread messages... isnt there supposed to be?

Well I'll be damned.  Thank you, again!!

the ps3, it only does everything including hides secrets from you.

Just sign off of PSN when you are playing an offline game such as Heavy Rain.

But even if you don't sign in, he can still see the games, that you have played from your trophy list.

Not if you dont sync the trophies lol