I also have a problem with my DeWalt 18v DC 925-XE. I think that the adaptor that screws the chuck into the drill is bent. (It is a Rohm, steel chuck with terrific holding strength.) If I open the chuck fully there is no screw at the bottom, just a flat surface. There are also no flats, for a spanner in between the chuck and the drill.
Normally I would expect the chuck to be removed as Steve has suggested but this is different.
Rob
December 2009