Dear Les
You may not be able to sand the floor, but you can remove all the old finish with a chemical stripper, for more about this please read my article on this in the Floored News section.
You may be able instead, to save the old finish, do various tests on the old finish as suggested in the second part of the floor maintenance article in the same section. And lastly be sure to read about my thoughts on the Orbital Floor sander in the case in point section.
You see there are many alternatives to just sanding a floor. And by the way if you do intend to strip the floor to the bare wood, and want a fast dry finish read my article on the Dura Seal 1000 water based finish. As always your Most humble servant, Joseph, the Wood Floor Doctor.
You may also find these articles helpful:
1. Product Reviews - DuraSeal 1000
2. Orbital Floor Sander
3. Should I sand the wood floors myself or hire a pro
4. Floor Types And Finishes
5. How To Take Care Of Your Health And Safety when Installing, Finishing, Repairing or Cleaning your wood floors