Yes they are irritating (though once done no more irritation), that is a problem within avast 6.0.1000, depending how you installed it (update over avast5 or clean install, etc. The gadget might have been located in the shared gadget folder, because of that would be reinstated as it is a shared resource upon reboot.

This has by all accounts been resolved in the current pre-release build of avast 6.0. But if you have already removed it that isn’t going to make any difference.