Posting a new thread as per request by Mister Fitzer.
In regards to the issue of not being able to join parties and/or use private chat functions.
I had this same issue for the first time last night. My friend and I both updated on the same day last week. The night we updated, everything worked perfectly the entire time.
Last night when we got on, everything seemed to work fine except for anything chat related. We couldn't join each other's party no matter which one of us started it first. And neither of us could get private chat to work. Playing online (BF3) and being connected to Live was working as usual.
We both reset the consoles, routers, and modems. Our NAT settings should not be an issue because neither of us have changed them since we got our routers. Everything XBOX related has seemed to work flawlessly up until last night.
In addition to that, we just signed on this evening to try our luck again. We both cleared our memory caches before getting online. The problem still exists.