I believe the problem lies in the fact that the program that is used to do the updates (avast.setup - this is really the name of the executable - no .exe extension) does NOT exist on the disk most of the time. It is temporarily flushed to the disk, launched and consequently deleted after it completes – this happens with each and every update attempt.

So I think Sygate somehow cannot cope with this scenario – what particularly iritates it is the absence of the avast.setup file on the disk…