Sorry but I can't make the dump because I have no SCROLL-LOCK key on my notebook's keyboard.
I tried to reboot with the 120406-0 update and now even the desktop appeared - I could only a black screen with a lonely mouse pointer on it. So I re-installed my Avast again.
I guess you added something new or special since the 120404-1 update. Maybe you tried to improve the rootkit scanning? Please, remove that "improvement" as soon as possible.
BTW, when I tried to reboot for the first time (with the 120404-1 update), I was prompted that TaskEng hangs and prevents from the shutting down.