I've been using Avast for some time now and have been very happy with it. Just recently though for reasons unknown Windows Security Center has stopped recognizing avast. When I boot up, I get the little red shield icon in my task tray with the message "Antivirus software might not be installed." Avast has been running fine on my machine for months. What's changed?
The machine in question is running Windows XP Home, and Avast version 4.6.744. It has all the latest Windows updates, and I can see the following running in the task manager: ashDisp.exe, ashMaiSv.exe, ashServ.exe, ashWebSv.exe, and ashUpdSv.exe. I have another machine running Windows XP Pro which also uses Avast and is not experiencing the problem.
I've tried uninstalling and reinstalling Avast a couple of times to no effect. Any ideas what the problem might be?