This has been happening to me for a while now and I can't find anyone else asking about it so I'm guessing it's something wrong on my end. It started doing it on windows xp and I'm running windows 7 now and it's still doing it. Sometimes I can go through a whole session without it locking up and sometimes it does it right away. As far as I can tell it's not a specific action that causes it to lock as it does it when I'm using items and other times it does it in the middle of adventuring. Mafia stops responding and the relay browser stops working and I have to end the task. It doesn't create a debug log when it locks. I'm currently using build 7790 but it's been doing it for the last few months with various versions. I'm using Windows 7 32-bit and the java page says "You have the recommended Java installed (1.7.0)."