Screw that sucker down!The floor probably wasn't glued and nailed properly in the first place.Don't know about putting glueon the screws,kind of like lock-tight on engine bolts?Can't hurt but very time consuming.Get an electric screwgun,2 inch deck or drywall screws,6inch apart in the field,4inch apart on the seams.Can't think of any thingelse you can do. Luck