I don't mean to continue this old topic. I am posting actually so to stop it (and any new post like "I have the same problem" should be avoided and a new topic should be started).
For anyone reading this topic, and JFYI (and not so you can keep posting), such messages can show up when:
A_ making hardware changes (not Avast related).
B_ the validation / registration of Windows has been "compromised". This can also happen when updating Windows (specially with SP updates). In this case, uninstall Avast, update Windows, reboot, update Windows, reboot... until no updates show up at all. Then re-validate Windows (by network revalidation or by phone with MS or OEM). Only *then* reinstall Avast.
C_ using Windows Starter Edition and trying to use "advanced" features. If AIS (for example) is installed, it would probably try to use such an advance feature "not allowed" under Windows Starter Edition. In addition, the restrictions are not exactly the same in each version and build of Windows, but in any case any *Starter* Edition of Windows is indeed limited, and not "all" features of other Windows Editions can be used. This is also not so related to Avast.
And of course, as usual, if you have (or HAD ) any other security tool (like the ones pre-installed in laptops / notebooks and alike) that is not compatible with Avast, please use the appropriate removal tool before installing Avast.
Thank you for NOT re-posting in this old topic.