Happens all the time. Be patient and get used to it, or use another AV.
Be patient is right. I made the mistake of doing a manual update, as
described on the website. All seemed to go well, but afterwards the
control centre icon no longer appeared in the systray, and task
manager showed that it was not loaded. All attempts to load it
manually failed - it just beeped and did nothing.
I thought that the update must have corrupted something and decided to
uninstall and reinstall the program, at which I hit a Catch-22 that
was almost beyond belief: all attempts to do so, from Windows'
add-remove programs or the uninstall link in the AVG program group
produced a message complaining that Setup can't proceed because AVG is
already installed, and that it should be uninstalled first. In other
words, it wouldn't let me uninstall unless I uninstalled first.
I must have installed and uninstalled hundreds of programs over the
years and have never come across idiocy like this before. It took
ages to manually delete what seemed to be hundreds of AVG entries from
the registry in order to remove all traces of the program from my
system.
I've now switched to Avast, whose free Home edition is much more
configurable.