Sorry but I have had absolutely no lockups on my 928 since the update. Everything has been completely solid. The only quirk I have seen is the Music app gets confused over a couple old classical music Christmas albums - never shows the correct title for the specific songs through the console in my car. It is only a couple albums though and I think it is just failing to identify them correctly and its subsequent guesses are off base.
Have you installed the Microsoft Field Medic App? That might give a clue as to the source in the system logs? BTW, were you on the WP8 OS or the DP version?