Chabad - Was the Lubavitcher Rebbe infallible?

Rabbi Oliver has 3 posting on his blog asserting that the Rebbe or at least his father-in-law was infallible.

I just contacted an old friend Rabbi Eli Touger who is a well known Lubavitch translator and is accessible on the Chabad website for queries in English.

I wrote the following:

[...] A Chabadnik told me there is a sicha where the Rebbe said he had been fooled by someone - and thus he made a mistake. Do you know where this is?

Rabbi Touger replied

That I don't know, but just recently there was a sichah printed in Dvar Malchus where the Rebbe was explaining why when Rosh Chodesh Av fell on Shabbos, the week before he made a mistake he said טעות היה בידי and read two haftorahs on the previous Shabbos. [...]