I have had my floors down for a year and I have been cleaning them with the cleaner from the manufacturer and they look like they have a film on them. I also have cats and they leave paw marks on the floor. I am thinking it is because of the film. What can I clean the floor with that will take the film off and be safe to the surface of the floor?

Also I have noticed a couple boards which are nailed down in my loft are getting raised places in them were the grain is in the wood. Is it difficult to change out the boards (and would the boards around them get damaged) or would it be better to overlook the flaws? There are 5 boards in different areas.

Make sure that cleaner is really a cleaner and not a "refresher". The bottle must say hardwood floor CLEANER, and nothing else. Individual boards can be replaced by a experienced pro. This is not a typical DIY job, especially if the floor was glued down.