Re: Dull& Worn floors after 5 years !
Welcome to the world of Minwax polys. I'm surprised that you were able to get a decent finish to begin with, my experience with Minwax is less than stellar.
You might be able to go over the top of the Minwax with a different product, but before you start broad application, do a test in a small, inconspicuous area to make sure there are no compatibility issues. The best bet would be to sand off the existing finish and start from scratch. Oil based polys are generally better for floors because they're harder and more durable. I cannot recommend a particular product for you, I'm not familiar with floor polys.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!