Accounts with zero posts and zero activity during the last months will be deleted periodically to fight SPAM!
Are you still able to interact with the editor tabs (with the mouse) ?If yes, this issue might be fixed in trunk (svn r6924).
Just a small thing: In the Help->About dialog it says: "Build Dec 28, 2010".
In all previous nightlies it's the nightly build release date. Did it change now?