Avast! 9.0.2006.159, Windows Home Premium 64 bit.
Icon was showing earlier today, then did not reappear after a restart. Tried a second restart, no icon.
Ran Avast! repair in Programs and Features, restarted, icon appeared.
Needed to restart yet again, no Avast! icon. Tried one more restart, no icon.
Each time that there is no icon, Notification Area Icons indicates that Avast! is running, but that that the icon is inactive.
Assistance, suggestions, words of incantation to be recited to ameliorate the reclusiveness of the icon?
[Later] For reasons that need not be discussed here, as not really relevant, i have had to reboot the computer a few times over the past thirty or so minutes. I just finished the series of reboots, having solved the non-relevant problem, and I see the Avast! icon once again. Given that this involves computers, it is possible that the other problem (which involved a printer driver) was interfering with the Avast! icon. I shall keep watch over this, and shall report any further attempts by the icon to play hermit. Maybe, the not-really relevant problem was actually relevant.