i was experiencing a problem where i could not get a good internet connection for my ps3. i would connect and sign on to the ps network and after anywhere from 5 to 30 minutes i would be logged out. i would re-connect and it will happen again. i figured out that in order to solve the problem i had to disable my ps3 from searching for media servers.
i am thinking that what you are experiencing may have something to do with the updates though because it only changed when you updated it. so if you want you can try to reset it and see if it solves your problem. if it does then you know that it is the update that caused it.