I just began using Avast! 4 Home Edition on my computer running Windows XP Home, and I noticed that when my computer is first booting up, the Avast! icon in the system tray has a "disabled" symbol over it, and a few moments later, it becomes enabled. Is it normal for the antivirus to be disabled when the system is still being started? Does this cause a temporary lack of security during startup which would allow a virus to infect my computer? Are other antiviruses subject to the same issue? Thanks in advance.