First of all thanks for the hard work and for delivering this product. I have used this without any trouble in the past.
First of all I think it might be useful to tell you how I use it: I write the words without special accents or characters, and then I fix the words with the dictionary. (I use international US keyboard layout but live in Portugal, so also write often in portuguese).
I have problems with words like "nao" which recognizes as "ano, na, no, ao, nano". In my opnion the correct nao with ~ is closer than all the rest.
Also sometimes I receive suggestions in spanish, for example "condicoes" receives as first suggestion "condiciones" instead of the correct "condições".
I should stress that I use this in Thunderbird, and that I had no problem whatsoever in previous versions.