I am proud to say that I recently have overcome a serious case of functional fixedness and a mental set at the same time!
By now, the Zynga game "Words With Friends" has become extremely popular on facebook. It is a board game that involves scoring points by making words crossword-style while also using bonus spaces that boost the points, either for an individual letter or for an entire word. Rarely used letters are worth more points, but clever use of the bonus spaces can equally boost your score. So there are multiple options to solve the problem of scoring a whole load of points and beating your friends.
Here was my situation: My letters were arranged in front of me to form the word "vessel" in combination with letters already on the board. V is worth 5 points, and the word used up a lot of letters. However, I couldn't play this word with the V on a "double letter tile." I stared at the board for 10 minutes, trying to find a good word to use V in, since it scores so high. I scrambled the letters in front of me, and saw that I could make "saddles." Now this would score a lot less (the entire word is only worth 10 points), but I could play it over two "double word" tiles, which quadruples my score to 40 points!
In this example, the letter V was part of my mental set. I was convinced I had to use it. The functional fixedness was on the ordering of the letters. Because I had started thinking with words beginning with V, I never thought to start a word with S until I scrambled them up. I find that when coming up with words, whether for a board game, an essay, or a poem, the longer I have to think about it, the more problems I have with mental sets and functional fixedness.