ldei,
I do not wish to discount the fact that you are experiencing a problem.
However, computers do not change the way they run "out of the blue", they change because of changes made to them, more often than not by those controlling them.
avast has not changed on the 4 up to date Win XP SP2 machines it is running on in this location, it has not changed for the users I support in other locations on Win XP SP2 systems. All are running - just fine as usual.
I do not post this with any intent to annoy you, I am sure your frustration is real enough. If this were a widespread problem among the literally millions of avast users we would be seeing many more "me too" posts in this forum.
This is just a plea to work with the experienced members of this forum (who, by and large, are avast users ... just as you are) and, perhaps, input from the Alwil team - they are frequent participants in this forum. Oh, and a plea to keep it to one thread rather than expressing your frustration in multiple threads.