We have experienced a problem with the lemmatizer and the word "laundering". When the POS tag is noun (NN) it correctly returns laundering, but if the POS tag is NNP it returns "launder". Looking at http://wordnetweb.princeton.edu/perl/webwn?s=laundering&sub=Search+WordNet&o2=&o0=1&o8=1&o1=1&o7=&o5=&o9=&o6=&o3=&o4=&h= it should only return launder when it is a verb (VB).
@jonfogh , sorry for the very late reply.
I do not understand your comment. Please give more information about the problem.