thanks essexboy, craigb, davidr, schmidthouse for your help; your suggestions worked and my hard disk space is where i'd like it to be.
i believe i uninstalled grimefighter from one of the earlier versions of avast, so i'm not sure why it would have reappeared, but david, you were right. it was there and i unchecked it, along with ng and one or two of the other features.
again, thanks for your help!