Suspicious avast-installer-like window

Hi,

I’ve recently re-connected my home server running win xp to internet, connected to it with RDP (it was up all the time, untouched, simply banned on the router for two or three days) just to find out a avast installer-alike window present. Strangely it was in norwegian, and my system is polish, and… avast has already been installed there for quite a while.

Process Explorer says it’s an avastui.exe thread

Simple questions are:

  1. Should I be worried?
  2. What the hell happened?
  3. How should I adress this matter if it’s a threat?