No fix that I know of, it is a pain...I even emailed Samsung about it but got told to ring them up which is likely even more futile than emailing them, so I didn't bother. You can alternatively wait 60secs for the message to clear...the wait has increased my tea consumption somewhat.
It's not only 57Hz users it annoys, I believe PS3s throw up this message too (assumedly at 24Hz in BluRay movies). I seriously doubt there's anything retroactive Samsung could do without recalling the screens, I see no connection for firmware flashing and it's not like a TV which can update over the tuner.
I was looking into EDID and some flashing of monitors, it is possible to do it with a DVI cable :roll: . Don't ask me how or what but it is possible.