In terms of categories, the pope is only protected from error in matters of faith and morals (and then only under clearly delineated circumstances, ie, he is addressing the whole of the Church in his role as Successor to Peter, etc.). In the disciplines he proposes, he is, of course, as subject to error as anyone else, but even those disciplines enjoy a negative infallibility, insofar as the Church is incapable of legislating against Her own teaching. Nothing in what she imposes can, of itself, oppose Her. The disciplines of the Church may not be prudentially the best, but they cannot lead the faithful into impiety. Also, we owe the Supreme Pontiff our obedience.
That’s said, I’m a little concerned about the tone of some posters. There seems to be a notion that if we aren’t slavishly hanging off every gesture the Holy Father makes or every word that he says, we’re failing in our duties as Catholics. That isn’t true. It’s perfectly ok to believe (and to say) what one thinks (assuming we hew to charity in our speech) without being charged with a lack of trust in the Holy Spirit. One can cite several examples that have nothing to do with faith and morals: The pope’s views, which one assumes remain consistent, on the Falkland Islands is that it should be under Argentine sovereignity. Does one sin against the Holy Spirit when they assert that he’s wrong? If he actually made the remark to Monsignor Marini, regarding the mozetta, that is reported ("you put it on, Monsignor. Carnival is over’), do we sin against the Holy Spirit by observing that seems a bit brusque? A little rude? In light of the faithful service rendered by Msg. Marini as Master of Ceremonies to the Pontiff Emeritus in his attempted “reform of the reform” of the liturgy? I’m not a traditionalist by any means (I never attend the EF and have no particular longing for Latin), but do I sin against the Holy Spirit when I wonder why the Holy Father stood for the homily at his Mass (Popes traditionally sit to teach, as do/did bishops, that’s why we refer to the “seat of Saint Peter,” why we HAVE cathedrals, to house cathedras or bishop’s seats) or if he’s going to wear that same miter hereafter forever?
We owe the Holy Father our obedience where his writ runs, but he isn’t above charitable criticism.