Avast Anti-Virus Question

Does Avast Home Edition expire... My program shut down last night and said it was expired and prompted me to purchase the Pro version. It was strange because the screen would not go to the link when I would click it nor could I bring anything else up because the Avast notice seemed to be on top of everything. I even had to pull the Task Manager to the side as the Avast notification was even on top of that. And when I shut down the Avast notice my computer said your computer is now at risk and the tray icons were gone. When I open the security center it still says that my Anti Virus is on. And when I run the scanner online it is also current and updated.

So my question is do I have to uninstall my Avast and re-install? And if so, is Avast my best option or is there other free programs that are better?