I was one of the posters chirping in on a few threads about how my Avast would stop periodically, with no rhyme or reason.
Using ccCleaner, I cleaned out some things in the registry, including an entry under MUI Cache - missing MUI reference. (This was the only problem showing in the registry that had to to with Avast.)
The data column was:
c:\program files\Alwil\software\Avast 5\setup\avast.setup
and the registry key was:
HKCR\software\Microsoft\Windows\shellnoroam\MUI Cache
I did it about a day and a half ago, and Avast hasn’t shut off since. (Yeah!)
When it happened (was doing it maybe 4 or 5 times a day), I would get an entry in Events. Those are no longer showing either.
May be coincidental, probably is, but thought I would throw it out here. Someone else having the same problem might want to try it and report back here.