FREEZING PROBLEM FIXED
I too had a freezing issue and stumbled on a fix that worked for me.
First, I would freeze when I pressed the START button to open the menu and do something like change wardrobe. I noticed that both the SOCIAL and WWW wheels would spin for a moment, and then all would freeze, necessitating a shutdown with the power button and restart. Then of course the usual trouble report to Sony, and HDD repair would run before I was back in Home and doing it all over again.
I did all of the usual suggestions for freezing: cache, reinstall, everything else. No fix.
So, I looked in the SOCIAL menu and learned that if you have several requests to join clubs on your list, that list preloads behind the scene every time you press START. My list had over a dozen club-join requests, so the reload jammed things up because it is very slow. (no idea why Sony did not build this feature to handle more requests)
I deleted all of the requests to join other clubs, and the freezing problem completely cleared up.
My suggestions: keep only a few join requests outstanding to minimize the list preload time. If the club join-request list is not your cause of freezing, then closely observe what happens just before your freeze - whatever happens is the cause of your freeze. Dig into it!