The most expensive comma, ever.

For what it's worth, I agree with the Aliant Inc. people. I was taught that if a clause within a sentence is enclosed by commas (in this case, the "and thereafter for successive five year terms" part), then it can be removed from the sentence and still have the remaining bits make sense. With the aforementioned clause removed, the sentence reads "shall continue in force for a period of five years from the date it is made unless and until terminated by one year prior notice in writing by either party." See, it still makes sense.  Therefore the Aliant people are in the clear.

Damn though, I'd hate to be the person who either created the contract or edited it.