Sorry to be a nuisance but could you clarify what I need to do/check to find out if I have a good installation.
I've don't *seem* to have encountered any problems with auto updates (I had two in the space of 30 mins the other day!!!), but as I say, I'm totally confused now.
The situation is:
If you are running 4.1.280, you're ok.
The people with automatic updates had this update chain:
something -> 268 (Thursday, 18th) -> 268 (phony, Friday, 19th) -> 278 -> 280.
People without automatic updates and version 268 had:
something -> 268 (Thursday, 18th) -> 278 BUG BUG BUG BUG

But now, they're ok (at least we hope) with this chain:
something -> 268 (Thursday, 18th) -> 280 okay, okay, okay.

even with
something -> 268 (Thursday, 18th) -> 278 BUG BUG BUG BUG -> 280 okay, okay.

The problem lies in two bugs as I explained here:
http://www.avast.com/forum/index.php?board=2;action=display;threadid=1410