Rotation around the sun doesn't let earth to stop rotating itself, we are literally moving ever since the big bang and actually big bang never stopped and will continue.
About the sudden halt I should point out to UFOs that people describing sudden change of moving direction like going at 1000 miles per hour but in an instance going backwards without showing any signs of hitting the brakes :)
yeah, the ufos seem to have developed ways to manipulate the very fabric of space time itself!