AVAST deactivated itself

I have an older desktop that runs Windows XP. Yes, I know it is not supported anymore, but the computer has been working fine and I prefer XP; strongly dislike all new versions of windows. I use AVAST Internet Security version, purchased in October 15, 2013 with a one year subscription. My computer worked fine this morning, internet was fine and AVAST was fine. I get home this evening and despite the network saying that the internet connection is fine, when I click on FireFox a window appears that states the server has been reset and there is no internet connection available. While I am trying to check the IP address and trouble shoot this error, my AVAST screen pops up and says that AVAST has been deactivated. A second window pops up that states that AVAST has expired and I must renew to gain function back. The small round icon at the bottom right of the screen says that AVAST is working and my computer is protected.

Does anyone know what is happening here? Is this an AVAST problem? A virus?
Like I said my computer was fine this morning, no sketchy activity, I only checked email (did not click on any links or anything like that, only known text email) and I received no error messages.
I am not tech savy and I don’t know what to try next.
Please help! Thank you.

Repair avast!:

  1. Control Panel → Add/Remove programs → avast!
  2. Click on ‘Repair’.
  3. Follow instructions.
  4. Reboot.