What is your OS ?
This is usually an indication of the presence of another AV, what else did you install after the format ?

AVAST FAQ - Red Circle on avast icon. AAVM subsytem detected and RPC error. http://www.avast.com/eng/faq-other-questions.html#idt_1539 Try this and see if it is applicable.

You report installing avast 4.0, that is really old, the latest version is 4.7.871, if your version is 4.0 I suggest you download the latest version, uninstall, reboot and install the latest version.