Ken, the glue will be removed very quickly when you sand the floor in the course of refinishing. Just remove as much as possible with a floor scraper, then proceed normally with sanding. The glue wont be there for long. You may have some blinding of the sandpaper until the glue and old finish are stripped, so start with a fairly course grit paper and work to fine. Are you using the easier to control square ocillating sander or a drum sander?